Nanoparticulate megestrol formulations

ABSTRACT

The present invention is directed to nanoparticulate compositions comprising megestrol. The megestrol particles of the composition have an effective average particle size of less than about 2000 nm.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/878,623, filed Jun. 29, 2004, which is a continuation-in-part of U.S.patent application Ser. No. 10/412,669, filed Apr. 14, 2003, now U.S.Pat. No. 7,101,576, which claims the benefit of priority from U.S.Provisional Patent Application No. 60/371,680, filed Apr. 12, 2002, andU.S. Provisional Patent Application No. 60/430,348, filed Dec. 3, 2002.The contents of these applications are incorporated herein by referencein their entirety.

FIELD OF THE INVENTION

The present invention relates to a nanoparticulate compositioncomprising megestrol and preferably at least one surface stabilizerassociated with the surface of the drug. The nanoparticulate megestrolparticles have an effective average particle size of less than about2000 nm.

BACKGROUND OF THE INVENTION

A. Background Regarding Nanoparticulate Compositions

Nanoparticulate compositions, first described in U.S. Pat. No. 5,145,684(“the '684 patent”), are particles consisting of a poorly solubletherapeutic or diagnostic agent having adsorbed onto the surface thereofa non-crosslinked surface stabilizer. The '684 patent does not describenanoparticulate compositions of megestrol.

Methods of making nanoparticulate compositions are described, forexample, in U.S. Pat. Nos. 5,518,187 and 5,862,999, both for “Method ofGrinding Pharmaceutical Substances;” U.S. Pat. No. 5,718,388, for“Continuous Method of Grinding Pharmaceutical Substances;” and U.S. Pat.No. 5,510,118 for “Process of Preparing Therapeutic CompositionsContaining Nanoparticles.”

Nanoparticulate compositions are also described, for example, in U.S.Pat. No. 5,298,262 for “Use of Ionic Cloud Point Modifiers to PreventParticle Aggregation During Sterilization;” U.S. Pat. No. 5,302,401 for“Method to Reduce Particle Size Growth During Lyophilization;” U.S. Pat.No. 5,318,767 for “X-Ray Contrast Compositions Useful in MedicalImaging;” U.S. Pat. No. 5,326,552 for “Novel Formulation ForNanoparticulate X-Ray Blood Pool Contrast Agents Using High MolecularWeight Non-ionic Surfactants;” U.S. Pat. No. 5,328,404 for “Method ofX-Ray Imaging Using Iodinated Aromatic Propanedioates;” U.S. Pat. No.5,336,507 for “Use of Charged Phospholipids to Reduce NanoparticleAggregation;” U.S. Pat. No. 5,340,564 for “Formulations Comprising Olin10-G to Prevent Particle Aggregation and Increase Stability;” U.S. Pat.No. 5,346,702 for “Use of Non-Ionic Cloud Point Modifiers to MinimizeNanoparticulate Aggregation During Sterilization;” U.S. Pat. No.5,349,957 for “Preparation and Magnetic Properties of Very SmallMagnetic-Dextran Particles;” U.S. Pat. No. 5,352,459 for “Use ofPurified Surface Modifiers to Prevent Particle Aggregation DuringSterilization;” U.S. Pat. Nos. 5,399,363 and 5,494,683, both for“Surface Modified Anticancer Nanoparticles;” U.S. Pat. No. 5,401,492 for“Water Insoluble Non-Magnetic Manganese Particles as Magnetic ResonanceEnhancement Agents;” U.S. Pat. No. 5,429,824 for “Use of Tyloxapol as aNanoparticulate Stabilizer;” U.S. Pat. No. 5,447,710 for “Method forMaking Nanoparticulate X-Ray Blood Pool Contrast Agents Using HighMolecular Weight Non-ionic Surfactants;” U.S. Pat. No. 5,451,393 for“X-Ray Contrast Compositions Useful in Medical Imaging;” U.S. Pat. No.5,466,440 for “Formulations of Oral Gastrointestinal Diagnostic X-RayContrast Agents in Combination with Pharmaceutically Acceptable Clays;”U.S. Pat. No. 5,470,583 for “Method of Preparing NanoparticleCompositions Containing Charged Phospholipids to Reduce Aggregation;”U.S. Pat. No. 5,472,683 for “Nanoparticulate Diagnostic Mixed CarbamicAnhydrides as X-Ray Contrast Agents for Blood Pool and Lymphatic SystemImaging;” U.S. Pat. No. 5,500,204 for “Nanoparticulate Diagnostic Dimersas X-Ray Contrast Agents for Blood Pool and Lymphatic System Imaging;”U.S. Pat. No. 5,518,738 for “Nanoparticulate NSAID Formulations;” U.S.Pat. No. 5,521,218 for “Nanoparticulate Iododipamide Derivatives for Useas X-Ray Contrast Agents;” U.S. Pat. No. 5,525,328 for “NanoparticulateDiagnostic Diatrizoxy Ester X-Ray Contrast Agents for Blood Pool andLymphatic System Imaging;” U.S. Pat. No. 5,543,133 for “Process ofPreparing X-Ray Contrast Compositions Containing Nanoparticles;” U.S.Pat. No. 5,552,160 for “Surface Modified NSAID Nanoparticles;” U.S. Pat.No. 5,560,931 for “Formulations of Compounds as NanoparticulateDispersions in Digestible Oils or Fatty Acids;” U.S. Pat. No. 5,565,188for “Polyalkylene Block Copolymers as Surface Modifiers forNanoparticles;” U.S. Pat. No. 5,569,448 for “Sulfated Non-ionic BlockCopolymer Surfactant as Stabilizer Coatings for NanoparticleCompositions;” 5,571,536 for “Formulations of Compounds asNanoparticulate Dispersions in Digestible Oils or Fatty Acids;” U.S.Pat. No. 5,573,749 for “Nanoparticulate Diagnostic Mixed CarboxylicAnydrides as X-Ray Contrast Agents for Blood Pool and Lymphatic SystemImaging;” 5,573,750 for “Diagnostic Imaging X-Ray Contrast Agents;” U.S.Pat. No. 5,573,783 for “Redispersible Nanoparticulate Film Matrices WithProtective Overcoats;” U.S. Pat. No. 5,580,579 for “Site-specificAdhesion Within the GI Tract Using Nanoparticles Stabilized by HighMolecular Weight, Linear Poly(ethylene Oxide) Polymers;” U.S. Pat. No.5,585,108 for “Formulations of Oral Gastrointestinal Therapeutic Agentsin Combination with Pharmaceutically Acceptable Clays;” U.S. Pat. No.5,587,143 for “Butylene Oxide-Ethylene Oxide Block CopolymersSurfactants as Stabilizer Coatings for Nanoparticulate Compositions;”U.S. Pat. No. 5,591,456 for “Milled Naproxen with HydroxypropylCellulose as Dispersion Stabilizer;” U.S. Pat. No. 5,593,657 for “NovelBarium Salt Formulations Stabilized by Non-ionic and AnionicStabilizers;” U.S. Pat. No. 5,622,938 for “Sugar Based Surfactant forNanocrystals;” U.S. Pat. No. 5,628,981 for “Improved Formulations ofOral Gastrointestinal Diagnostic X-Ray Contrast Agents and OralGastrointestinal Therapeutic Agents;” U.S. Pat. No. 5,643,552 for“Nanoparticulate Diagnostic Mixed Carbonic Anhydrides as X-Ray ContrastAgents for Blood Pool and Lymphatic System Imaging;” U.S. Pat. No.5,718,388 for “Continuous Method of Grinding Pharmaceutical Substances;”U.S. Pat. No. 5,718,919 for “Nanoparticles Containing the R(−)Enantiomerof Ibuprofen;” U.S. Pat. No. 5,747,001 for “Aerosols ContainingBeclomethasone Nanoparticle Dispersions;” U.S. Pat. No. 5,834,025 for“Reduction of Intravenously Administered Nanoparticulate FormulationInduced Adverse Physiological Reactions;” U.S. Pat. No. 6,045,829“Nanocrystalline Formulations of Human Immunodeficiency Virus (HIV)Protease Inhibitors Using Cellulosic Surface Stabilizers;” 6,068,858 for“Methods of Making Nanocrystalline Formulations of HumanImmunodeficiency Virus (HIV) Protease Inhibitors Using CellulosicSurface Stabilizers;” U.S. Pat. No. 6,153,225 for “InjectableFormulations of Nanoparticulate Naproxen;” U.S. Pat. No. 6,165,506 for“New Solid Dose Form of Nanoparticulate Naproxen;” U.S. Pat. No.6,221,400 for “Methods of Treating Mammals Using NanocrystallineFormulations of Human Immunodeficiency Virus (HIV) Protease Inhibitors;”U.S. Pat. No. 6,264,922 for “Nebulized Aerosols Containing NanoparticleDispersions;” 6,267,989 for “Methods for Preventing Crystal Growth andParticle Aggregation in Nanoparticle Compositions;” U.S. Pat. No.6,270,806 for “Use of PEG-Derivatized Lipids as Surface Stabilizers forNanoparticulate Compositions;” U.S. Pat. No. 6,316,029 for “RapidlyDisintegrating Solid Oral Dosage Form,” U.S. Pat. No. 6,375,986 for“Solid Dose Nanoparticulate Compositions Comprising a SynergisticCombination of a Polymeric Surface Stabilizer and Dioctyl SodiumSulfosuccinate,” U.S. Pat. No. 6,428,814 for “BioadhesiveNanoparticulate Compositions Having Cationic Surface Stabilizers;” U.S.Pat. No. 6,431,478 for “Small Scale Mill;” and 6,432,381 for “Methodsfor Targeting Drug Delivery to the Upper and/or Lower GastrointestinalTract,” all of which are specifically incorporated by reference. Inaddition, U.S. Patent Application No. 20020012675 A1, published on Jan.31, 2002, for “Controlled Release Nanoparticulate Compositions,”describes nanoparticulate compositions, and is specifically incorporatedby reference.

Amorphous small particle compositions are described, for example, inU.S. Pat. No. 4,783,484 for “Particulate Composition and Use Thereof asAntimicrobial Agent;” U.S. Pat. No. 4,826,689 for “Method for MakingUniformly Sized Particles from Water-Insoluble Organic Compounds;” U.S.Pat. No. 4,997,454 for “Method for Making Uniformly-Sized Particles FromInsoluble Compounds;” U.S. Pat. No. 5,741,522 for “Ultrasmall,Non-aggregated Porous Particles of Uniform Size for Entrapping GasBubbles Within and Methods;” and U.S. Pat. No. 5,776,496, for“Ultrasmall Porous Particles for Enhancing Ultrasound Back Scatter.”

B. Background Regarding Megestrol

Megestrol acetate, also known as17α-acetyloxy-6-methylpregna-4,6-diene-3,20-dione, is a syntheticprogestin with progestational effects similar to those of progesterone.It is used in abortion, endometriosis, and menstrual disorders. It isalso used in a variety of situations including treatment of breastcancer, contraception, and hormone replacement therapy inpost-menopausal women. Megestrol acetate is also frequently prescribedas an appetite enhancer for patients in a wasting state, such as HIVwasting, cancer wasting, or anorexia. In combination with ethynylestradiol it acts as an oral contraceptive. It is also administered tosubjects after castration.

Megestrol acetate is marketed by Par Pharmaceuticals, Inc. and under thebrand name Megace® by Bristol Myers Squibb Co. Typical commercialformulations are relatively large volume. For example, ParPharmaceuticals, Inc. megestrol acetate oral suspension contains 40 mgof micronized megestrol acetate per ml, and the package insertrecommends an initial adult dosage of megestrol acetate oral suspensionof 800 mg/day (20 mL/day). The commercial formulations of megestrolacetate are highly viscous suspensions, which have a relatively longresidence time in the mouth and any tubing. Highly viscous substancesare not well accepted by patient populations, particularly patientssuffering wasting and those that are intubated.

U.S. Pat. No. 6,028,065 for “Flocculated Suspension of MegestrolAcetate,” assigned to Pharmaceutical Resources, Inc. (Spring Valley,N.Y.), describes oral pharmaceutical micronized megestrol acetatecompositions in the form of a stable flocculated suspension in water.The compositions comprise at least one compound selected from the groupconsisting of polyethylene glycol, propylene glycol, glycerol, andsorbitol; and a surfactant, wherein polysorbate and polyethylene glycolare not simultaneously present. U.S. Pat. No. 6,268,356, also for“Flocculated Suspension of Megestrol Acetate,” and assigned toPharmaceutical Resources, Inc., describes methods of treating aneoplastic condition comprising administering the composition of U.S.Pat. No. 6,028,065.

Another company that has developed a megestrol formulation is Eurand(Milan, Italy). Eurand's formulation is a modified form of megestrolacetate having increased bioavailability. Eurand structurally modifiespoorly soluble drugs to increase their bioavailability. Seewww.eurand.com. For megestrol acetate, Eurand uses its' “Biorise”process, in which a New Physical Entity (NPE) is created by physicallybreaking down megestrol's crystal lattice. This results in drugnanocrystals and/or amorphous drug, which are then stabilized withbiologically inert carriers. Eurand uses three types of carriers:swellable microparticles, composite swellable microparticles, andcyclodextrins. See e.g., http://www.eurand.com/page.php?id=39. Such adelivery system can be undesirable, as “breaking down” an active agent'scrystalline structure can modify the activity of the active agent. Adrug delivery system which does not alter the structure of the activeagent is preferable.

Among the progestins, megestrol acetate is one of the few that can beadministered orally because of its reduced first-pass (hepatic)metabolism, compared to the parent hormone. In addition, it is claimedto be superior to 19-nor compounds as an antifertility agent because ithas less effect on the endometrium and vagina. See Stedman's MedicalDictionary, 25^(th) Ed., page 935 (Williams & Wilkins, MD 1990).

There is a need in the art for megestrol formulations which exhibitincreased bioavailability, less variability, and/or less viscosity ascompared to conventional microparticulate megestrol formulations. Thepresent invention satisfies these needs.

SUMMARY OF THE INVENTION

The invention relates to nanoparticulate megestrol compositions. Thecompositions comprise megestrol and preferably at least one surfacestabilizer associated with the surface of the megestrol particles. Thenanoparticulate megestrol particles have an effective average particlesize of less than about 2000 nm.

Another aspect of the invention is directed to pharmaceuticalcompositions comprising a nanoparticulate megestrol composition of theinvention. The pharmaceutical compositions preferably comprisemegestrol, at least one surface stabilizer, and a pharmaceuticallyacceptable carrier, as well as any desired excipients.

This invention further discloses a method of making a nanoparticulatemegestrol composition according to the invention. Such a methodcomprises contacting megestrol particles and at least one surfacestabilizer for a time and under conditions sufficient to provide ananoparticulate megestrol composition. The one or more surfacestabilizers can be contacted with megestrol either before, during, orafter size reduction of the megestrol.

The present invention is also directed to methods of treatment using thenanoparticulate compositions of the invention for conditions such asendometriosis, dysmenorrhea, hirsutism, uterine bleeding, neoplasticdiseases, methods of appetite enhancement, contraception, hormonereplacement therapy, and treating patients following castration. Suchmethods comprises administering to a subject a therapeutically effectiveamount of a nanoparticulate megestrol composition according to theinvention.

Finally, the present invention is directed to megestrol acetatecompositions with improved physical (viscosity) and pharmacokineticprofiles (such as less variability) over traditional forms of megestrolacetate.

Both the foregoing general description and the following detaileddescription are exemplary and explanatory and are intended to providefurther explanation of the invention as claimed. Other objects,advantages, and novel features will be readily apparent to those skilledin the art from the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Illustrates viscosity in units of mPa s as a function ofconcentration. Circles indicate the experimental values and the lineillustrates the expected trend;

FIG. 2: Illustrates viscosity in units of Pa s as a function of shearrate for two commercial samples, Bristol Myers Squibb and ParPharmaceuticals, both at an active concentration of 40 mg/mL; and

FIG. 3: Shows a photograph of, from left to right, a nanoparticulatedispersion of megestrol acetate, a commercial sample of megestrolacetate marketed by Par Pharmaceuticals, and a commercial sample ofmegestrol acetate marketed by Bristol Myers Squibb.

FIG. 4: The figure graphically shows the comparative bioavailability(via plasma concentration (ng/mL)) of several nanoparticulate megestrolcompositions (575 mg/5 ml, 625 mg/5 ml and 675 mg/5 ml) versus aconventional megestrol acetate marketed by Bristol Myers Squibb.

FIG. 5: The figure graphically shows on a natural log scale thecomparative bioavailability (via plasma concentration (ng/mL)) ofseveral nanoparticulate megestrol compositions (575 mg/5 ml, 625 mg/5 mland 675 mg/5 ml) versus a conventional megestrol acetate marketed byBristol Myers Squibb.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to nanoparticulate compositionscomprising megestrol particles having an effective average particle sizeof less than about 2 microns. The compositions comprise megestrol andpreferably at least one surface stabilizer associated with the surfaceof the drug.

As taught in the '684 patent, not every combination of surfacestabilizer and active agent will result in a stable nanoparticulatecomposition. It was surprisingly discovered that stable nanoparticulatemegestrol compositions can be made.

For example, nanoparticulate megestrol compositions with hydroxypropylmethylcellulose (HPMC) and sodium lauryl sulfate (SLS) as surfacestabilizers remained stable in an electrolyte solution mimicking thephysiological pH of the stomach. Nanoparticulate megestrol compositionscomprising HPMC and SLS are stable for several weeks at temperatures upto 40° C. with only minimal particle size growth. In addition,nanoparticulate megestrol compositions with hydroxypropylcellulose (HPC)and dioctyl sodium sulfosuccinate (DOSS) as surface stabilizers, HPMCand DOSS as surface stabilizers, polyvinylpyrrolidone (PVP) and DOSS assurface stabilizers, and Plasdone® S630 and DOSS as surface stabilizerswere stable in electrolyte fluids and exhibited acceptable physicalstability at 5° C. for 4 weeks. (Plasdone® S630 (ISP) is a randomcopolymer of vinyl acetate and vinyl pyrrolidone.) Moreover, thenanoparticulate megestrol/HPMC/SLS and nanoparticulatemegestrol/HPMC/DOSS compositions also exhibited acceptable physicalstability at 25° C. and 40° C. for 4 weeks.

Advantages of the nanoparticulate megestrol compositions of theinvention include, but are not limited to: (1) low viscosity liquidnanoparticulate megestrol dosage forms; (2) for liquid nanoparticulatemegestrol compositions having a low viscosity—better subject compliancedue to the perception of a lighter formulation which is easier toconsume and digest; (3) for liquid nanoparticulate megestrolcompositions having a low viscosity—ease of dispensing because one canuse a cup or a syringe; (4) faster onset of action; (5) smaller doses ofmegestrol required to obtain the same pharmacological effect as comparedto conventional microcrystalline forms of megestrol; (6) increasedbioavailability as compared to conventional microcrystalline forms ofmegestrol; (7) substantially similar pharmacokinetic profiles of thenanoparticulate megestrol compositions when administered in the fedversus the fasted state; (8) bioequivalency of the nanoparticulatemegestrol compositions when administered in the fed versus the fastedstate; (9) redispersibility of the nanoparticulate megestrol particlespresent in the compositions of the invention following administration;(10) bioadhesive nanoparticulate megestrol compositions; (11) improvedpharmacokinetic profiles, such as more rapid megestrol absorption,greater megestrol absorption, and longer megestrol dose retention in theblood following administration; (12) the nanoparticulate megestrolcompositions can be used in conjunction with other active agents; (13)the nanoparticulate megestrol compositions preferably exhibit anincreased rate of dissolution as compared to conventionalmicrocrystalline forms of megestrol; (14) improved performancecharacteristics for oral, intravenous, subcutaneous, or intramuscularinjection, such as higher dose loading and smaller tablet or liquid dosevolumes; (15) the nanoparticulate megestrol compositions are suitablefor parenteral administration; (16) the nanoparticulate megestrolcompositions can be sterile filtered; and (17) the nanoparticulatemegestrol compositions do not require organic solvents or pH extremes.

The present invention is described herein using several definitions, asset forth below and throughout the application.

“About” will be understood by persons of ordinary skill in the art andwill vary to some extent on the context in which the term is used. Ifthere are uses of the term which are not clear to persons of ordinaryskill in the art given the context in which it is used, “about” willmean up to plus or minus 10% of the particular term.

As used herein with reference to stable drug particles, “stable” meansthat the megestrol particles do not appreciably flocculate oragglomerate due to interparticle attractive forces or otherwise increasein particle size.

“Conventional active agents or drugs” refers to non-nanoparticulatecompositions of active agents or solubilized active agents or drugs.Non-nanoparticulate active agents have an effective average particlesize of greater than about 2 microns.

A. Preferred Characteristics of the Nanoparticulate MegestrolCompositions of the Invention

1. Low Viscosity

Typical commercial formulations of megestrol, such as Megace®, arerelatively large volume, highly viscous substances that are not wellaccepted by patient populations, particularly subjects suffering fromwasting. “Wasting” is a condition in which a subject finds it difficultto eat because, for example, food makes the subject nauseous. A highlyviscous medicine is not compatible with treating such a condition, asfrequently the highly viscous substance can cause additional nausea.

Moreover, viscous solutions can be problematic in parenteraladministration because these solutions require a slow syringe push andcan stick to tubing. In addition, conventional formulations of poorlywater-soluble active agents, such as megestrol, tend to be unsafe forintravenous administration techniques, which are used primarily inconjunction with highly water-soluble substances.

Liquid dosage forms of the nanoparticulate megestrol compositions of theinvention provide significant advantages over conventional liquidmegestrol dosage forms. The low viscosity and silky texture of liquiddosage forms of the nanoparticulate megestrol compositions of theinvention results in advantages in both preparation and use. Theseadvantages include, for example: (1) better subject compliance due tothe perception of a lighter formulation which is easier to consume anddigest; (2) ease of dispensing because one can use a cup or a syringe;(3) potential for formulating a higher concentration of megestrolresulting in a smaller dosage volume and thus less volume for thesubject to consume; and (4) easier overall formulation concerns.

Liquid megestrol dosage forms which are easier to consume are especiallyimportant when considering juvenile patients, terminally ill patients,and patients suffering from gastrointestinal tract dysfunction or otherconditions where nausea and vomiting are symptoms. For example, patientssuffering from cancer or AIDS-related complications are commonlyhypermetabolic and, at various stages of disease, exhibitgastrointestinal dysfunction. Additionally, drugs used to treat theseconditions often cause nausea and vomiting. Viscous or grittyformulations, and those that require a relatively large dosage volume,are not well tolerated by patient populations suffering from wastingassociated with these diseases because the formulations can exacerbatenausea and encourage vomiting.

The viscosities of liquid dosage forms of nanoparticulate megestrolaccording to the invention are preferably less than about 1/200, lessthan about 1/175, less than about 1/150, less than about 1/125, lessthan about 1/100, less than about 1/75, less than about 1/50, or lessthan about 1/25 of existing commercial liquid oral megestrol acetatecompositions, e.g. Megace®, at about the same concentration per ml ofmegestrol.

Typically the viscosity of liquid nanoparticulate megestrol dosage formsof the invention is from about 175 mPa s to about 1 mPa s, from about150 mPa s to about 1 mPa, from about 125 mPa s to about 1 mPa s, fromabout 100 mPa s to about 1 mPa s, from about 75 mPa s to about 1 mPa s,from about 50 mPa s to about 1 mPa s, from about 25 mPa s to about 1 mPas, from about 15 mPa s to about 1 mPa s, or from about 5 mPa s to about1 mPa s. Such a viscosity is much more attractive for subjectconsumption and may lead to better overall subject compliance.

Viscosity is concentration and temperature dependent. Typically, ahigher concentration results in a higher viscosity, while a highertemperature results in a lower viscosity. Viscosity as defined aboverefers to measurements taken at about 20° C. (The viscosity of water at20° C. is 1 mPa s.) The invention encompasses equivalent viscositiesmeasured at different temperatures.

A viscosity of 1.5 mPa s for a nanoparticulate megestrol dispersionhaving a concentration of 30 mg/mL, measured at 20° C., was obtained bythe inventors. An equivalent viscosity at 4% active agent concentrationwould be 1.7 mPa s. Higher and lower viscosities can be obtained byvarying the temperature and concentration of megestrol.

Another important aspect of the invention is that the nanoparticulatemegestrol compositions of the invention are not turbid. “Turbid,” asused herein refers to the property of particulate matter that can beseen with the naked eye or that which can be felt as “gritty.” Thenanoparticulate megestrol compositions of the invention can be pouredout of or extracted from a container as easily as water, whereas aconventional standard commercial (i.e., non-nanoparticulate orsolubilized) megestrol liquid dosage form exhibits notably more“sluggish” characteristics.

The liquid formulations of this invention can be formulated for dosagesin any volume but preferably equivalent or smaller volumes than existingcommercial formulations.

2. Fast Onset of Activity

The use of conventional formulations of megestrol is not ideal due todelayed onset of action. In contrast, the nanoparticulate megestrolcompositions of the invention exhibit faster therapeutic effects.

Preferably, following administration the nanoparticulate megestrolcompositions of the invention have a T_(max) of less than about 5 hours,less than about 4.5 hours, less than about 4 hours, less than about 3.5hours, less than about 3 hours, less than about 2.75 hours, less thanabout 2.5 hours, less than about 2.25 hours, less than about 2 hours,less than about 1.75 hours, less than about 1.5 hours, less than about1.25 hours, less than about 1.0 hours, less than about 50 minutes, lessthan about 40 minutes, less than about 30 minutes, less than about 25minutes, less than about 20 minutes, less than about 15 minutes, or lessthan about 10 minutes.

3. Increased Bioavailability

The nanoparticulate megestrol compositions of the invention preferablyexhibit increased bioavailability and require smaller doses as comparedto prior conventional megestrol compositions administered at the samedose.

Any drug, including megestrol, can have adverse side effects. Thus,lower doses of megestrol which can achieve the same or bettertherapeutic effects as those observed with larger doses of conventionalmegestrol compositions are desired. Such lower doses can be realizedwith the nanoparticulate megestrol compositions of the invention becausethe greater bioavailability observed with the nanoparticulate megestrolcompositions as compared to conventional drug formulations means thatsmaller doses of drug are required to obtain the desired therapeuticeffect. Specifically, a once a day dose of about 375 mg/5 mL (75 mg/mL)of a nanoparticulate megestrol acetate composition is consideredequivalent to an 800 mg dose of Megace®.

Administration of nanoparticulate megestrol formulations of the presentinvention can exhibit bioavailability, as determined by AUC0-t, in anamount of about 3000 ng hr/ml to about 15,000 ng hr/ml, wherein Cmax isabout 300 ng/ml to about 1400 ng/ml, 1500 ng/ml, 1600 ng/ml, 1645 ng/mlor 1700 ng/ml in a fed human subject and AUC0-t in an amount of about2000 ng hr/ml to about 9000 ng hr/ml, wherein Cmax is about 300 ng/ml toabout 2000 ng/ml in a fasted human subject. Preferably, nanoparticulatemegestrol formulations of the present invention exhibit comparablebioavailability in a range of between about 75 and about 130%, morepreferably between about 80% and about 125%, of the specifiedtherapeutic parameter (e.g., AUC0-t or Cmax).

4. The Pharmacokinetic Profiles of the Nanoparticulate MegestrolCompositions of the Invention are not Substantially Affected by the Fedor Fasted State of the Subject Ingesting the Compositions

The invention encompasses nanoparticulate megestrol compositions whereinthe pharmacokinetic profile of the megestrol is not substantiallyaffected by the fed or fasted state of a subject ingesting thecomposition. This means that there is no substantial difference in thequantity of megestrol absorbed or the rate of megestrol absorption whenthe nanoparticulate megestrol compositions are administered in the fedversus the fasted state. Thus, the invention encompasses nanoparticulatemegestrol compositions that can substantially eliminate the effect offood on the pharmacokinetics of megestrol.

The difference in absorption of the nanoparticulate megestrolcomposition of the invention, when administered in the fed versus thefasted state, is less than about 35%, less than about 30%, less thanabout 25%, less than about 20%, less than about 15%, less than about10%, less than about 5%, or less than about 3%. This is an especiallyimportant feature in treating patients with difficulty in maintaining afed state.

In addition, preferably the difference in the rate of absorption (i.e.,T_(max)) of the nanoparticulate megestrol compositions of the invention,when administered in the fed versus the fasted state, is less than about100%, less than about 90%, less than about 80%, less than about 70%,less than about 60%, less than about 50%, less than about 40%, less thanabout 30%, less than about 20%, less than about 15%, less than about10%, less than about 5%, less than about 3%, or essentially nodifference.

Benefits of a dosage form which substantially eliminates the effect offood include an increase in subject convenience, thereby increasingsubject compliance, as the subject does not need to ensure that they aretaking a dose either with or without food.

5. Redispersibility Profiles of the Nanoparticulate MegestrolCompositions of the Invention

An additional feature of the nanoparticulate megestrol compositions ofthe invention is that the compositions redisperse such that theeffective average particle size of the redispersed megestrol particlesis less than about 2 microns. This is significant, as if uponadministration the nanoparticulate megestrol particles present in thecompositions of the invention did not redisperse to a substantiallynanoparticulate particle size, then the dosage form may lose thebenefits afforded by formulating megestrol into a nanoparticulateparticle size.

This is because nanoparticulate megestrol compositions benefit from thesmall particle size of megestrol; if the nanoparticulate megestrolparticles do not redisperse into the small particle sizes uponadministration, then “clumps” or agglomerated megestrol particles areformed. With the formation of such agglomerated particles, thebioavailability of the dosage form may fall.

Preferably, the redispersed megestrol particles of the invention have aneffective average particle size, by weight, of less than about 2microns, less than about 1900 nm, less than about 1800 nm, less thanabout 1700 nm, less than about 1600 nm, less than about 1500 nm, lessthan about 1400 nm, less than about 1300 nm, less than about 1200 nm,less than about 1100 nm, less than about 1000 nm, less than about 900nm, less than about 800 nm, less than about 700 nm, less than about 600nm, less than about 500 nm, less than about 400 nm, less than about 300nm, less than about 250 nm, less than about 200 nm, less than about 150nm, less than about 100 nm, less than about 4826-6925-0832.1 75 nm, orless than about 50 nm, as measured by light-scattering methods,microscopy, or other appropriate methods.

Moreover, the nanoparticulate megestrol compositions of the inventionexhibit dramatic redispersion of the nanoparticulate megestrol particlesupon administration to a mammal, such as a human or animal, asdemonstrated by reconstitution in a biorelevant aqueous media. Suchbiorelevant aqueous media can be any aqueous media that exhibit thedesired ionic strength and pH, which form the basis for the biorelevanceof the media. The desired pH and ionic strength are those that arerepresentative of physiological conditions found in the human body. Suchbiorelevant aqueous media can be, for example, aqueous electrolytesolutions or aqueous solutions of any salt, acid, or base, or acombination thereof, which exhibit the desired pH and ionic strength.

Biorelevant pH is well known in the art. For example, in the stomach,the pH ranges from slightly less than 2 (but typically greater than 1)up to 4 or 5. In the small intestine the pH can range from 4 to 6, andin the colon it can range from 6 to 8. Biorelevant ionic strength isalso well known in the art. Fasted state gastric fluid has an ionicstrength of about 0.1M while fasted state intestinal fluid has an ionicstrength of about 0.14. See e.g., Lindahl et al., “Characterization ofFluids from the Stomach and Proximal Jejunum in Men and Women,” Pharm.Res., 14 (4): 497-502 (1997).

It is believed that the pH and ionic strength of the test solution ismore critical than the specific chemical content. Accordingly,appropriate pH and ionic strength values can be obtained throughnumerous combinations of strong acids, strong bases, salts, single ormultiple conjugate acid-base pairs (i.e., weak acids and correspondingsalts of that acid), monoprotic and polyprotic electrolytes, etc.

Representative electrolyte solutions can be, but are not limited to, HClsolutions, ranging in concentration from about 0.001 to about 0.1 M, andNaCl solutions, ranging in concentration from about 0.001 to about 0.1M, and mixtures thereof. For example, electrolyte solutions can be, butare not limited to, about 0.1 M HCl or less, about 0.01 M HCl or less,about 0.001 M HCl or less, about 0.1 M NaCl or less, about 0.01 M NaClor less, about 0.001 M NaCl or less, and mixtures thereof. Of theseelectrolyte solutions, 0.01 M HCl and/or 0.1 M NaCl, are mostrepresentative of fasted human physiological conditions, owing to the pHand ionic strength conditions of the proximal gastrointestinal tract.

Electrolyte concentrations of 0.001 M HCl, 0.01 M HCl, and 0.1 M HClcorrespond to pH 3, pH 2, and pH 1, respectively. Thus, a 0.01 M HClsolution simulates typical acidic conditions found in the stomach. Asolution of 0.1 M NaCl provides a reasonable approximation of the ionicstrength conditions found throughout the body, including thegastrointestinal fluids, although concentrations higher than 0.1 M maybe employed to simulate fed conditions within the human GI tract.

Exemplary solutions of salts, acids, bases or combinations thereof,which exhibit the desired pH and ionic strength, include but are notlimited to phosphoric acid/phosphate salts+sodium, potassium and calciumsalts of chloride, acetic acid/acetate salts+sodium, potassium andcalcium salts of chloride, carbonic acid/bicarbonate salts+sodium,potassium and calcium salts of chloride, and citric acid/citratesalts+sodium, potassium and calcium salts of chloride.

6. Bioadhesive Nanoparticulate Megestrol Compositions

Bioadhesive nanoparticulate megestrol compositions of the inventioncomprise at least one cationic surface stabilizer, which are describedin more detail below. Bioadhesive formulations of megestrol exhibitexceptional bioadhesion to biological surfaces, such as mucous.

In the case of bioadhesive nanoparticulate megestrol compositions, theterm “bioadhesion” is used to describe the adhesion between thenanoparticulate megestrol compositions and a biological substrate (i.e.gastrointestinal mucin, lung tissue, nasal mucosa, etc.). See e.g., U.S.Pat. No. 6,428,814 for “Bioadhesive Nanoparticulate Compositions HavingCationic Surface Stabilizers,” which is specifically incorporated byreference.

The bioadhesive megestrol compositions of the invention are useful inany situation in which it is desirable to apply the compositions to abiological surface. The bioadhesive megestrol compositions coat thetargeted surface in a continuous and uniform film which is invisible tothe naked human eye.

A bioadhesive nanoparticulate megestrol composition slows the transit ofthe composition, and some megestrol particles would also most likelyadhere to tissue other than the mucous cells and therefore give aprolonged exposure to megestrol, thereby increasing absorption and thebioavailability of the administered dosage.

7. Pharmacokinetic Profiles of the Nanoparticulate MegestrolCompositions of the Invention

The present invention also provides compositions of nanoparticulatemegestrol having a desirable pharmacokinetic profile when administeredto mammalian subjects. The desirable pharmacokinetic profile of thenanoparticulate megestrol compositions comprise the parameters: (1) thatthe T_(max) of megestrol, when assayed in the plasma of the mammaliansubject, is less than about 5 hours; and (2) a C_(max) of megestrol isgreater than about 30 ng/ml. Preferably, the T_(max) parameter of thepharmacokinetic profile is not greater than about 3 hours. Mostpreferably, the T_(max) parameter of the pharmacokinetic profile is notgreater than about 2 hours.

The desirable pharmacokinetic profile, as used herein, is thepharmacokinetic profile measured after the initial dose of megestrol.For example, in a subject receiving 40 mg of megestrol four times a day,the T_(max) and C_(max) after the initial dose must be less than about 5hours and greater than about 30 ng/ml, respectively. The compositionscan be formulated in any way as described below.

Current formulations of megestrol include oral suspensions and tablets.According to the package insert of Megace®, the pharmacokinetic profileof the oral suspension contains parameters such that the median T_(max)is 5 hours and the mean C_(max) is 753 ng/ml. Further, the T_(max) andC_(max) for the Megace® mg tablet, after the initial dose, is 2.2 hoursand 27.6 ng/ml, respectively. Physicians Desk Reference, 55th Ed., 2001.The nanoparticulate megestrol compositions of the inventionsimultaneously improve upon at least the T_(max) and C_(max) parametersof the pharmacokinetic profile of megestrol.

In one embodiment, a threshold blood plasma concentration of megestrolof about 700 ng/ml is attained in less than about 5 hours afteradministration of the formulation, and preferably not greater than about3 hours.

Preferably, the T_(max) of an administered dose of a nanoparticulatemegestrol composition is less than that of a conventional standardcommercial non-nanoparticulate megestrol composition, administered atthe same dosage. In addition, preferably the C_(max) of ananoparticulate megestrol composition is greater than the C_(max) of aconventional standard commercial non-nanoparticulate megestrolcomposition, administered at the same dosage.

A preferred nanoparticulate megestrol composition of the inventionexhibits in comparative pharmacokinetic testing with a standardcommercial formulation of megestrol, such as Megace® oral suspension ortablet from Bristol Myers Squibb, a T_(max) which is less than about100%, less than about 90%, less than about 80%, less than about 70%,less than about 60%, less than about 50%, less than about 40%, less thanabout 30%, less than about 25%, less than about 20%, less than about15%, or less than about 10% of the T_(max) exhibited by the standardcommercial formulation of megestrol.

A preferred nanoparticulate megestrol composition of the inventionexhibits in comparative pharmacokinetic testing with a standardcommercial formulation of megestrol, such as Megace® oral suspension ortablet from Bristol Myers Squibb, a C_(max) which is greater than about5%, greater than about 10%, greater than about 15%, greater than about20%, greater than about 30%, greater than about 40%, greater than about50%, greater than about 60%, greater than about 70%, greater than about80%, greater than about 90%, greater than about 100%, greater than about110%, greater than about 120%, greater than about 130%, greater thanabout 140%, greater than about 150%, greater than about 200%, greaterthan about 500% or greater than about 800% than the C_(max) exhibited bythe standard commercial formulation of megestrol.

There is no critical upper limit of blood plasma concentration so longas the dosage amounts set out below are not significantly exceeded. Asuitable dose of megestrol, administered according to the method of theinvention, is typically in the range of about 1 mg/day to about 1000mg/day, or from about 40 mg/day to about 800 mg/day. In one embodiment,a nanoparticulate megestrol composition is administered at a dose of 575mg/day. In other embodiments, the nanoparticulate megestrol compositionis administered at doses of 625 mg/day or 675 mg/day. Preferably, thetherapeutically effective amount of the nanoparticulate megestrolcompositions of the invention is about ⅙, ⅕, ¼, ⅓, ½, ⅔, ¾ or ⅚ of thetherapeutically effective amount of existing commercial megestrolformulations.

Any standard pharmacokinetic protocol can be used to determine bloodplasma concentration profile in humans following administration of ananoparticulate megestrol composition, and thereby establish whetherthat composition meets the pharmacokinetic criteria set out herein. Forexample, a randomized single-dose crossover study can be performed usinga group of healthy adult human subjects. The number of subjects shouldbe sufficient to provide adequate control of variation in a statisticalanalysis, and is typically about 10 or greater, although for certainpurposes a smaller group can suffice. Each subject receives by oraladministration at time zero a single dose (e.g., 300 mg) of a testformulation of megestrol, normally at around 8 am following an overnightfast. The subjects continue to fast and remain in an upright positionfor about 4 hours after administration of the megestrol formulation.Blood samples are collected from each subject prior to administration(e.g., 15 minutes) and at several intervals after administration. Forthe present purpose it is preferred to take several samples within thefirst hour, and to sample less frequently thereafter. Illustratively,blood samples could be collected at 15, 30, 45, 60, and 90 minutes afteradministration, then every hour from 2 to 10 hours after administration.Additional blood samples may also be taken later, for example at 12 and24 hours after administration. If the same subjects are to be used forstudy of a second test formulation, a period of at least 7 days shouldelapse before administration of the second formulation. Plasma isseparated from the blood samples by centrifugation and the separatedplasma is analyzed for megestrol by a validated high performance liquidchromatography (HPLC) procedure, such as for example Garver et al., J.Pharm. Sci. 74(6):664-667 (1985), the entirety of which is herebyincorporated by reference. Plasma concentrations of megestrol referencedherein are intended to mean total megestrol concentrations includingboth free and bound megestrol.

Any formulation giving the desired pharmacokinetic profile is suitablefor administration according to the present methods. Exemplary types offormulations giving such profiles are liquid dispersions and solid doseforms of nanoparticulate megestrol. Dispersions of megestrol have provento be stable at temperatures up to 50° C. If the liquid dispersionmedium is one in which the nanoparticulate megestrol has very lowsolubility, the nanoparticulate megestrol particles are present assuspended particles. The smaller the megestrol particles, the higher theprobability that the formulation will exhibit the desiredpharmacokinetic profile.

8. Combination Pharmacokinetic Profile Compositions

In yet another embodiment of the invention, a first nanoparticulatemegestrol composition providing a desired pharmacokinetic profile isco-administered, sequentially administered, or combined with at leastone other megestrol composition that generates a desired differentpharmacokinetic profile. More than two megestrol compositions can beco-administered, sequentially administered, or combined. While the firstmegestrol composition has a nanoparticulate particle size, theadditional one or more megestrol compositions can be nanoparticulate,solubilized, or have a conventional microparticulate particle size.

For example, a first megestrol composition can have a nanoparticulateparticle size, conferring a short T_(max) and typically a higherC_(max). This first megestrol composition can be combined,co-administered, or sequentially administered with a second compositioncomprising: (1) megestrol having a larger (but still nanoparticulate asdefined herein) particle size, and therefore exhibiting slowerabsorption, a longer T_(max), and typically a lower C_(max); or (2) amicroparticulate or solubilized megestrol composition, exhibiting alonger T_(max), and typically a lower C_(max).

The second, third, fourth, etc., megestrol compositions can differ fromthe first, and from each other, for example: (1) in the effectiveaverage particle sizes of megestrol; or (2) in the dosage of megestrol.Such a combination composition can reduce the dose frequency required.

If the second megestrol composition has a nanoparticulate particle size,then preferably the megestrol particles of the second composition haveat least one surface stabilizer associated with the surface of the drugparticles. The one or more surface stabilizers can be the same as ordifferent from the surface stabilizer(s) present in the first megestrolcomposition.

Preferably where co-administration of a “fast-acting” formulation and a“longer-lasting” formulation is desired, the two formulations arecombined within a single composition, for example a dual-releasecomposition.

9. Combination Active Agent Compositions

The invention encompasses the nanoparticulate megestrol compositions ofthe invention formulated or co-administered with one or morenon-megestrol active agents, which are either conventional (solubilizedor microparticulate) or nanoparticulate. Methods of using suchcombination compositions are also encompassed by the invention. Thenon-megestrol active agents can be present in a crystalline phase, anamorphous phase, a semi-crystalline phase, a semi-amorphous phase, or amixture thereof.

The compound to be administered in combination with a nanoparticulatemegestrol composition of the invention can be formulated separately fromthe nanoparticulate megestrol composition or co-formulated with thenanoparticulate megestrol composition. Where a nanoparticulate megestrolcomposition is co-formulated with a second active agent, the secondactive agent can be formulated in any suitable manner, such asimmediate-release, rapid-onset, sustained-release, or dual-release form.

If the non-megestrol active agent has a nanoparticulate particle sizei.e., a particle size of less than about 2 microns, then preferably itwill have one or more surface stabilizers associated with the surface ofthe active agent. In addition, if the active agent has a nanoparticulateparticle size, then it is preferably poorly soluble and dispersible inat least one liquid dispersion media. By “poorly soluble” it is meantthat the active agent has a solubility in a liquid dispersion media ofless than about 30 mg/mL, less than about 20 mg/mL, less than about 10mg/mL, or less than about 1 mg/mL. Useful liquid dispersion mediasinclude, but are not limited to, water, aqueous salt solutions,safflower oil, and solvents such as ethanol, t-butanol, hexane, andglycol.

Such non-megestrol active agents can be, for example, a therapeuticagent. A therapeutic agent can be a pharmaceutical agent, includingbiologics. The active agent can be selected from a variety of knownclasses of drugs, including, for example, amino acids, proteins,peptides, nucleotides, anti-obesity drugs, central nervous systemstimulants, carotenoids, corticosteroids, elastase inhibitors,anti-fungals, oncology therapies, anti-emetics, analgesics,cardiovascular agents, anti-inflammatory agents, such as NSAIDs andCOX-2 inhibitors, anthelmintics, anti-arrhythmic agents, antibiotics(including penicillins), anticoagulants, antidepressants, antidiabeticagents, antiepileptics, antihistamines, antihypertensive agents,antimuscarinic agents, antimycobacterial agents, antineoplastic agents,immunosuppressants, antithyroid agents, antiviral agents, anxiolytics,sedatives (hypnotics and neuroleptics), astringents, alpha-adrenergicreceptor blocking agents, beta-adrenoceptor blocking agents, bloodproducts and substitutes, cardiac inotropic agents, contrast media,corticosteroids, cough suppressants (expectorants and mucolytics),diagnostic agents, diagnostic imaging agents, diuretics, dopaminergics(antiparkinsonian agents), haemostatics, immunological agents, lipidregulating agents, muscle relaxants, parasympathomimetics, parathyroidcalcitonin and biphosphonates, prostaglandins, radio-pharmaceuticals,sex hormones (including steroids), anti-allergic agents, stimulants andanoretics, sympathomimetics, thyroid agents, vasodilators, andxanthines.

A description of these classes of active agents and a listing of specieswithin each class can be found in Martindale's The Extra Pharmacopoeia,31^(st) Edition (The Pharmaceutical Press, London, 1996), specificallyincorporated by reference. The active agents are commercially availableand/or can be prepared by techniques known in the art.

Exemplary nutraceuticals and dietary supplements are disclosed, forexample, in Roberts et al., Nutraceuticals: The Complete Encyclopedia ofSupplements, Herbs, Vitamins, and Healing Foods (American NutraceuticalAssociation, 2001), which is specifically incorporated by reference.Dietary supplements and nutraceuticals are also disclosed in Physicians'Desk Reference for Nutritional Supplements, 1st Ed. (2001) and ThePhysicians' Desk Reference for Herbal Medicines, 1st Ed. (2001), both ofwhich are also incorporated by reference. A nutraceutical or dietarysupplement, also known as a phytochemical or functional food, isgenerally any one of a class of dietary supplements, vitamins, minerals,herbs, or healing foods that have medical or pharmaceutical effects onthe body.

Exemplary nutraceuticals or dietary supplements include, but are notlimited to, lutein, folic acid, fatty acids (e.g., DHA and ARA), fruitand vegetable extracts, vitamin and mineral supplements,phosphatidylserine, lipoic acid, melatonin, glucosamine/chondroitin,Aloe Vera, Guggul, glutamine, amino acids (e.g., arginine, iso-leucine,leucine, lysine, methionine, phenylanine, threonine, tryptophan, andvaline), green tea, lycopene, whole foods, food additives, herbs,phytonutrients, antioxidants, flavonoid constituents of fruits, eveningprimrose oil, flax seeds, fish and marine animal oils, and probiotics.Nutraceuticals and dietary supplements also include bio-engineered foodsgenetically engineered to have a desired property, also known as“pharmafoods.”

10. Sterile Filtered Nanoparticulate Megestrol Compositions

The nanoparticulate megestrol compositions of the invention can besterile filtered. This obviates the need for heat sterilization, whichcan harm or degrade megestrol, as well as result in crystal growth andparticle aggregation.

Sterile filtration can be difficult because of the required smallparticle size of the composition. Filtration is an effective method forsterilizing homogeneous solutions when the membrane filter pore size isless than or equal to about 0.2 microns (200 nm) because a 0.2 micronfilter is sufficient to remove essentially all bacteria. Sterilefiltration is normally not used to sterilize conventional suspensions ofmicron-sized megestrol because the megestrol particles are too large topass through the membrane pores.

A sterile nanoparticulate megestrol dosage form is particularly usefulin treating immunocompromised patients, infants or juvenile patients,and the elderly, as these patient groups are the most susceptible toinfection caused by a non-sterile liquid dosage form.

Because the nanoparticulate megestrol compositions of the invention canbe sterile filtered, and because the compositions can have a very smallmegestrol effective average particle size, the compositions are suitablefor parenteral administration.

11. Miscellaneous Benefits of the Nanoparticulate Megestrol Compositionsof the Invention

The nanoparticulate megestrol compositions preferably exhibit anincreased rate of dissolution as compared to conventionalmicrocrystalline forms of megestrol. In addition, the compositions ofthe invention exhibit improved performance characteristics for oral,intravenous, subcutaneous, or intramuscular injection, such as higherdose loading and smaller tablet or liquid dose volumes. Moreover, thenanoparticulate megestrol compositions of the invention do not requireorganic solvents or pH extremes.

Another benefit of the nanoparticulate megestrol compositions of theinvention is that is was surprisingly discovered that uponadministration, nanoparticulate compositions of megestrol acetate reachtherapeutic blood levels within one dose. This is in dramatic contrastto the current commercially available megestrol acetate composition(Megace® by Bristol Myers Squibb Co.), which requires multiple doses,administered over several days to a week, to build up to a therapeuticlevel of drug in the blood stream.

B. Compositions

The invention provides compositions comprising nanoparticulate megestrolparticles and preferably at least one surface stabilizer. The one ormore surface stabilizers are preferably associated with the surface ofthe megestrol particles. Surface stabilizers useful herein preferably donot chemically react with the megestrol particles or itself. Individualmolecules of the surface stabilizer are essentially free ofintermolecular cross-linkages.

The present invention also includes nanoparticulate megestrolcompositions together with one or more non-toxic physiologicallyacceptable carriers, adjuvants, or vehicles, collectively referred to ascarriers. The compositions can be formulated for parenteral injection(e.g., intravenous, intramuscular, or subcutaneous), oral administrationin solid, liquid, or aerosol form, vaginal, nasal, rectal, ocular, local(powders, ointments or drops), buccal, intracisternal, intraperitoneal,or topical administration, and the like.

1. Megestrol Particles

As used herein the term megestrol, which is the active ingredient in thecomposition, is used to mean megestrol, megestrol acetate(17α-acetyloxy-6-methylpregna-4,6-diene-3,20-dione), or a salt thereof.The megestrol particles can be present in a crystalline phase, anamorphous phase, a semi-crystalline phase, a semi-amorphous phase, or amixture thereof.

Megestrol acetate is well known in the art and is readily recognized byone of ordinary skill. Generally, megestrol is used for treating breastcancer, endometrial cancer and, less frequently, prostate cancer.Megestrol is also frequently used as an appetite stimulant for patientsin a wasting state, such as HIV wasting, cancer wasting, and anorexia.Megestrol may be used for other indications where progestins aretypically used, such as hormone replacement therapy in post-menopausalwomen and oral contraception. Further, megestrol may be used for ovariansuppression in several conditions such as endometriosis, hirsutism,dysmenorrhea, and uterine bleeding, as well as uterine cancer, cervicalcancer, and renal cancer. Megestrol is also used in patients followingcastration.

2. Surface Stabilizers

The choice of a surface stabilizer for megestrol is non-trivial.Accordingly, the present invention is directed to the surprisingdiscovery that nanoparticulate megestrol compositions can be made.

Combinations of more than one surface stabilizer can be used in theinvention. Preferred surface stabilizers include, but are not limitedto, hydroxypropyl methylcellulose, hydroxypropylcellulose,polyvinylpyrrolidone, random copolymers of vinyl pyrrolidone and vinylacetate, sodium lauryl sulfate, dioctylsulfosuccinate or a combinationthereof. Preferred primary surface stabilizers include, but are notlimited to, hydroxypropyl methylcellulose, hydroxypropylcellulose,polyvinylpyrrolidone, random copolymers of vinyl pyrrolidone and vinylacetate, or a combination thereof. Preferred secondary surfacestabilizers include, but are not limited to, sodium lauryl sulfate anddioctylsulfosuccinate.

Other surface stabilizers which can be employed in the inventioninclude, but are not limited to, known organic and inorganicpharmaceutical excipients. Such excipients include various polymers, lowmolecular weight oligomers, natural products, and surfactants. Surfacestabilizers include nonionic, cationic, ionic, and zwitterionicsurfactants.

Representative examples of surface stabilizers include hydroxypropylmethylcellulose, hydroxypropylcellulose, polyvinylpyrrolidone, sodiumlauryl sulfate, dioctylsulfosuccinate, gelatin, casein, lecithin(phosphatides), dextran, gum acacia, cholesterol, tragacanth, stearicacid, benzalkonium chloride, calcium stearate, glycerol monostearate,cetostearyl alcohol, cetomacrogol emulsifying wax, sorbitan esters,polyoxyethylene alkyl ethers (e.g., macrogol ethers such as cetomacrogol1000), polyoxyethylene castor oil derivatives, polyoxyethylene sorbitanfatty acid esters (e.g., the commercially available Tweens® such ase.g., Tween 20® and Tween 80® (ICI Specialty Chemicals)); polyethyleneglycols (e.g., Carbowaxs 3550® and 934® (Union Carbide)),polyoxyethylene stearates, colloidal silicon dioxide, phosphates,carboxymethylcellulose calcium, carboxymethylcellulose sodium,methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulosephthalate, noncrystalline cellulose, magnesium aluminium silicate,triethanolamine, polyvinyl alcohol (PVA),4-(1,1,3,3-tetramethylbutyl)-phenol polymer with ethylene oxide andformaldehyde (also known as tyloxapol, superione, and triton),poloxamers (e.g., Pluronics F68® and F108®, which are block copolymersof ethylene oxide and propylene oxide); poloxamines (e.g., Tetronic908®, also known as Poloxamine 908®, which is a tetrafunctional blockcopolymer derived from sequential addition of propylene oxide andethylene oxide to ethylenediamine (BASF Wyandotte Corporation,Parsippany, N.J.)); Tetronic 1508® (T-1508) (BASF WyandotteCorporation), Tritons X-200®, which is an alkyl aryl polyether sulfonate(Rohm and Haas); Crodestas F-110®, which is a mixture of sucrosestearate and sucrose distearate (Croda Inc.);p-isononylphenoxypoly-(glycidol), also known as Olin-lOG® or Surfactant10-G® (Olin Chemicals, Stanford, Conn.); Crodestas SL-40® (Croda, Inc.);and SA9OHCO, which is C₁₈H₃₇CH₂(CON(CH₃)—CH₂(CHOH)₄(CH₂0H)₂ (EastmanKodak Co.); decanoyl-N-methylglucamide; n-decyl β-D-glucopyranoside;n-decyl β-D-maltopyranoside; n-dodecyl β-D-glucopyranoside; n-dodecylβ-D-maltoside; heptanoyl-N-methylglucamide;n-heptyl-β-D-glucopyranoside; n-heptyl β-D-thioglucoside; n-hexylβ-D-glucopyranoside; nonanoyl-N-methylglucamide; n-noylβ-D-glucopyranoside; octanoyl-N-methylglucamide;n-octyl-p-D-glucopyranoside; octyl β-D-thioglucopyranoside;PEG-phospholipid, PEG-cholesterol, PEG-cholesterol derivative,PEG-vitamin A, PEG-vitamin E, lysozyme, random copolymers of vinylpyrrolidone and vinyl acetate, and the like.

Examples of useful cationic surface stabilizers include, but are notlimited to, polymers, biopolymers, polysaccharides, cellulosics,alginates, phospholipids, and nonpolymeric compounds, such aszwitterionic stabilizers, poly-n-methylpyridinium, anthryul pyridiniumchloride, cationic phospholipids, chitosan, polylysine,polyvinylimidazole, polybrene, polymethylmethacrylatetrimethylammoniumbromide bromide (PMMTMABr), hexyldesyltrimethylammoniumbromide (HDMAB), and polyvinylpyrrolidone-2-dimethylaminoethylmethacrylate dimethyl sulfate.

Other useful cationic stabilizers include, but are not limited to,cationic lipids, sulfonium, phosphonium, and quartemary ammoniumcompounds, such as stearyltrimethylammonium chloride,benzyl-di(2-chloroethyl)ethylammonium bromide, coconut trimethylammonium chloride or bromide, coconut methyl dihydroxyethyl ammoniumchloride or bromide, decyl triethyl ammonium chloride, decyl dimethylhydroxyethyl ammonium chloride or bromide, C₁₂₋₁₅dimethyl hydroxyethylammonium chloride or bromide, coconut dimethyl hydroxyethyl ammoniumchloride or bromide, myristyl trimethyl ammonium methyl sulphate, lauryldimethyl benzyl ammonium chloride or bromide, lauryl dimethyl(ethenoxy)₄ ammonium chloride or bromide, N-alkyl (C₁₂₋₁₈)dimethylbenzylammonium chloride, N-alkyl (C₁₄₋₁₈)dimethyl-benzyl ammonium chloride,N-tetradecylidmethylbenzyl ammonium chloride monohydrate, dimethyldidecyl ammonium chloride, N-alkyl and (C₁₂₋₁₄) dimethyl 1-napthylmethylammonium chloride, trimethylammonium halide, alkyl-trimethylammoniumsalts and dialkyl-dimethylammonium salts, lauryl trimethyl ammoniumchloride, ethoxylated alkyamidoalkyldialkylammonium salt and/or anethoxylated trialkyl ammonium salt, dialkylbenzene dialkylammoniumchloride, N-didecyldimethyl ammonium chloride,N-tetradecyldimethylbenzyl ammonium, chloride monohydrate,N-alkyl(C₁₂₋₁₄) dimethyl 1-naphthylmethyl ammonium chloride anddodecyldimethylbenzyl ammonium chloride, dialkyl benzenealkyl ammoniumchloride, lauryl trimethyl ammonium chloride, alkylbenzyl methylammonium chloride, alkyl benzyl dimethyl ammonium bromide, C₁₂, C₁₅, C₁₇trimethyl ammonium bromides, dodecylbenzyl triethyl ammonium chloride,poly-diallyldimethylammonium chloride (DADMAC), dimethyl ammoniumchlorides, alkyldimethylammonium halogenides, tricetyl methyl ammoniumchloride, decyltrimethylammonium bromide, dodecyltriethylammoniumbromide, tetradecyltrimethylammonium bromide, methyl trioctylammoniumchloride (ALIQUAT 336™), POLYQUAT 10™, tetrabutylammonium bromide,benzyl trimethylammonium bromide, choline esters (such as choline estersof fatty acids), benzalkonium chloride, stearalkonium chloride compounds(such as stearyltrimonium chloride and Di-stearyldimonium chloride),cetyl pyridinium bromide or chloride, halide salts of quaternizedpolyoxyethylalkylamines, MIRAPOL™ and ALKAQUAT™ (Alkaril ChemicalCompany), alkyl pyridinium salts; amines, such as alkylamines,dialkylamines, alkanolamines, polyethylenepolyamines,N,N-dialkylaminoalkyl acrylates, and vinyl pyridine, amine salts, suchas lauryl amine acetate, stearyl amine acetate, alkylpyridinium salt,and alkylimidazolium salt, and amine oxides; imide azolinium salts;protonated quaternary acrylamides; methylated quaternary polymers, suchas poly[diallyl dimethylammonium chloride] and poly-[N-methyl vinylpyridinium chloride]; and cationic guar.

Such exemplary cationic surface stabilizers and other useful cationicsurface stabilizers are described in J. Cross and E. Singer, CationicSurfactants: Analytical and Biological Evaluation (Marcel Dekker, 1994);P. and D. Rubingh (Editor), Cationic Surfactants: Physical Chemistry(Marcel Dekker, 1991); and J. Richmond, Cationic Surfactants: OrganicChemistry, (Marcel Dekker, 1990).

Particularly preferred nonpolymeric primary stabilizers are anynonpolymeric compound, such benzalkonium chloride, a carbonium compound,a phosphonium compound, an oxonium compound, a halonium compound, acationic organometallic compound, a quartemary phosphorous compound, apyridinium compound, an anilinium compound, an ammonium compound, ahydroxylammonium compound, a primary ammonium compound, a secondaryammonium compound, a tertiary ammonium compound, and quartemary ammoniumcompounds of the formula NR₁R₂R₃R₄ ⁽⁺⁾. For compounds of the formulaNR₁R₂R₃R₄ ⁽⁺⁾:

-   -   (i) none of R₁-R₄ are CH₃;    -   (ii) one of R₁-R₄ is CH₃;    -   (iii) three of R₁-R₄ are CH₃;    -   (iv) all of R₁-R₄ are CH₃;    -   (v) two of R₁-R₄ are CH₃, one of R₁-R₄ is C₆H₅CH₂, and one of        R₁-R₄ is an alkyl chain of seven carbon atoms or less;    -   (vi) two of R₁-R₄ are CH₃, one of R₁-R₄ is C₆H₅CH₂, and one of        R₁-R₄ is an alkyl chain of nineteen carbon atoms or more;    -   (vii) two of R₁-R₄ are CH₃ and one of R₁-R₄ is the group        C₆H₅(CH₂), where n>1;    -   (viii) two of R₁-R₄ are CH₃, one of R₁-R₄ is C₆H₅CH₂, and one of        R₁-R₄ comprises at least one heteroatom;    -   (ix) two of R₁-R₄ are CH₃, one of R₁-R₄ is C₆H₅CH₂, and one of        R₁-R₄ comprises at least one halogen;    -   (x) two of R₁-R₄ are CH₃, one of R₁-R₄ is C₆H₅CH₂, and one of        R₁-R₄ comprises at least one cyclic fragment;    -   (xi) two of R₁-R₄ are CH₃ and one of R₁-R₄ is a phenyl ring; or    -   (xii) two of R₁-R₄ are CH₃ and two of R₁-R₄ are purely aliphatic        fragments.

Such compounds include, but are not limited to, behenalkonium chloride,benzethonium chloride, cetylpyridinium chloride, behentrimoniumchloride, lauralkonium chloride, cetalkonium chloride, cetrimoniumbromide, cetrimonium chloride, cethylamine hydrofluoride,chlorallylmethenamine chloride (Quaternium-15), distearyldimoniumchloride (Quaternium-5), dodecyl dimethyl ethylbenzyl ammoniumchloride(Quaternium-14), Quaternium-22, Quaternium-26, Quaternium-18hectorite, dimethylaminoethylchloride hydrochloride, cysteinehydrochloride, diethanolammonium POE (10) oletyl ether phosphate,diethanolammonium POE (3)oleyl ether phosphate, tallow alkoniumchloride, dimethyl dioctadecylammoniumbentonite, stearalkonium chloride,domiphen bromide, denatonium benzoate, myristalkonium chloride,laurtrimonium chloride, ethylenediamine dihydrochloride, guanidinehydrochloride, pyridoxine HCl, iofetamine hydrochloride, megluminehydrochloride, methylbenzethonium chloride, myrtrimonium bromide,oleyltrimonium chloride, polyquatemium-1, procainehydrochloride,cocobetaine, stearalkonium bentonite, stearalkoniumhectonite, stearyltrihydroxyethyl propylenediamine dihydrofluoride, tallowtrimoniumchloride, and hexadecyltrimethyl ammonium bromide.

Most of these surface stabilizers are known pharmaceutical excipientsand are described in detail in the Handbook of PharmaceuticalExcipients, published jointly by the American Pharmaceutical Associationand The Pharmaceutical Society of Great Britain (The PharmaceuticalPress, 2000), specifically incorporated by reference. The surfacestabilizers are commercially available and/or can be prepared bytechniques known in the art.

3. Other Pharmaceutical Excipients

Pharmaceutical megestrol compositions according to the invention mayalso comprise one or more binding agents, filling agents, lubricatingagents, suspending agents, sweeteners, flavoring agents, preservatives,buffers, wetting agents, disintegrants, effervescent agents, and otherexcipients. Such excipients are known in the art.

Examples of filling agents are lactose monohydrate, lactose anhydrous,and various starches; examples of binding agents are various cellulosesand cross-linked polyvinylpyrrolidone, microcrystalline cellulose, suchas Avicel® PH101 and Avicel® PH102, microcrystalline cellulose, andsilicified microcrystalline cellulose (ProSolv SMCCT™).

Suitable lubricants, including agents that act on the flowability of thepowder to be compressed, are colloidal silicon dioxide, such as Aerosil®200, talc, stearic acid, magnesium stearate, calcium stearate, andsilica gel.

Examples of sweeteners are any natural or artificial sweetener, such assucrose, xylitol, sodium saccharin, cyclamate, aspartame, and acsulfame.Examples of flavoring agents are Magnasweet® (trademark of MAFCO),bubble gum flavor, and fruit flavors, and the like.

Examples of preservatives are potassium sorbate, methylparaben,propylparaben, benzoic acid and its salts, other esters ofparahydroxybenzoic acid such as butylparaben, alcohols such as ethyl orbenzyl alcohol, phenolic compounds such as phenol, or quarternarycompounds such as benzalkonium chloride.

Suitable diluents include pharmaceutically acceptable inert fillers,such as microcrystalline cellulose, lactose, dibasic calcium phosphate,saccharides, and/or mixtures of any of the foregoing. Examples ofdiluents include microcrystalline cellulose, such as Avicel® PH101 andAvicel® PH102; lactose such as lactose monohydrate, lactose anhydrous,and Pharmatose® DCL21; dibasic calcium phosphate such as Emcompress®;mannitol; starch; sorbitol; sucrose; and glucose.

Suitable disintegrants include lightly crosslinked polyvinylpyrrolidone, corn starch, potato starch, maize starch, and modifiedstarches, croscarmellose sodium, cross-povidone, sodium starchglycolate, and mixtures thereof.

Examples of effervescent agents are effervescent couples such as anorganic acid and a carbonate or bicarbonate. Suitable organic acidsinclude, for example, citric, tartaric, malic, fumaric, adipic,succinic, and alginic acids and anhydrides and acid salts. Suitablecarbonates and bicarbonates include, for example, sodium carbonate,sodium bicarbonate, potassium carbonate, potassium bicarbonate,magnesium carbonate, sodium glycine carbonate, L-lysine carbonate, andarginine carbonate. Alternatively, only the sodium bicarbonate componentof the effervescent couple may be present.

4. Nanoparticulate Megestrol or Active Agent Particle Size

As used herein, particle size is determined on the basis of the weightaverage particle size as measured by conventional particle sizemeasuring techniques well known to those skilled in the art. Suchtechniques include, for example, sedimentation field flow fractionation,photon correlation spectroscopy, light scattering, and diskcentrifugation.

The compositions of the invention comprise nanoparticulate megestrolparticles which have an effective average particle size of less thanabout 2000 nm (i.e., 2 microns). In other embodiments of the invention,the megestrol particles have an effective average particle size of lessthan about 1900 nm, less than about 1800 nm, less than about 1700 nm,less than about 1600 nm, less than about 1500 nm, less than about 1400nm, less than about 1300 nm, less than about 1200 nm, less than about1100 nm, less than about 1000 nm, less than about 900 nm, less thanabout 800 nm, less than about 700 nm, less than about 600 nm, less thanabout 500 nm, less than about 400 nm, less than about 300 nm, less thanabout 250 nm, less than about 200 nm, less than about 150 nm, less thanabout 100 nm, less than about 75 nm, or less than about 50 nm, whenmeasured by the above techniques.

If the nanoparticulate megestrol composition additionally comprises oneor more non-megestrol nanoparticulate active agents, then such activeagents have an effective average particle size of less than about 2000nm (i.e., 2 microns). In other embodiments of the invention, thenanoparticulate non-megestrol active agents can have an effectiveaverage particle size of less than about 1900 nm, less than about 1800nm, less than about 1700 nm, less than about 1600 nm, less than about1500 nm, less than about 1400 nm, less than about 1300 nm, less thanabout 1200 nm, less than about 1100 nm, less than about 1000 nm, lessthan about 900 nm, less than about 800 nm, less than about 700 nm, lessthan about 600 nm, less than about 500 nm, less than about 400 nm, lessthan about 300 nm, less than about 250 nm, less than about 200 nm, lessthan about 150 nm, less than about 100 nm, less than about 75 nm, orless than about 50 nm, as measured by light-scattering methods,microscopy, or other appropriate methods.

By “an effective average particle size of less than about 2000 nm” it ismeant that at least 50% of the nanoparticulate megestrol ornanoparticulate non-megestrol active agent particles have a particlesize of less than about 2000 nm, by weight, when measured by theabove-noted techniques. Preferably, at least about 70%, about 90%, about95%, or about 99% of the nanoparticulate megestrol or nanoparticulatenon-megestrol active agent particles have a particle size of less thanthe effective average, i.e., less than about 2000 nm, less than about1900 nm, less than about 1800 nm, etc.

If the nanoparticulate megestrol composition is combined with aconventional or microparticulate megestrol composition or non-megestrolactive agent composition, then such a composition is either solubilizedor has an effective average particle size of greater than about 2microns. By “an effective average particle size of greater than about 2microns” it is meant that at least 50% of the conventional megestrol ornon-megestrol active agent particles have a particle size of greaterthan about 2 microns, by weight, when measured by the above-notedtechniques. In other embodiments of the invention, at least about 70%,about 90%, about 95%, or about 99% of the conventional megestrol ornon-megestrol active agent particles have a particle size greater thanabout 2 microns.

5. Concentration of Nanoparticulate Megestrol and Surface Stabilizers

The relative amounts of nanoparticulate megestrol and one or moresurface stabilizers can vary widely. The optimal amount of theindividual components can depend, for example, the hydrophiliclipophilic balance (HLB), melting point, and the surface tension ofwater solutions of the stabilizer, etc.

The concentration of megestrol can vary from about 99.5% to about0.001%, from about 95% to about 0.1%, or from about 90% to about 0.5%,by weight, based on the total combined dry weight of the megestrol andat least one surface stabilizer, not including other excipients.

The concentration of the at least one surface stabilizer can vary fromabout 0.5% to about 99.999%, from about 5.0% to about 99.9%, or fromabout 10% to about 99.5%, by weight, based on the total combined dryweight of the megestrol and at least one surface stabilizer, notincluding other excipients.

If a combination of two or more surface stabilizers is employed in thecomposition, the concentration of the at least one primary surfacestabilizer can vary from about 0.01% to about 99.5%, from about 0.1% toabout 95%, or from about 0.5% to about 90%, by weight, based on thetotal combined dry weight of the megestrol, at least one primary surfacestabilizer, and at least one secondary surface stabilizer, not includingother excipients. In addition, the concentration of the at least onesecondary surface stabilizer can vary from about 0.01% to about 99.5%,from about 0.1% to about 95%, or from about 0.5% to about 90%, byweight, based on the total combined dry weight of the megestrol, atleast one primary surface stabilizer, and at least one secondary surfacestabilizer, not including other excipients.

C. Methods of Making Nanoparticulate Megestrol Compositions

The nanoparticulate megestrol compositions can be made using, forexample, milling, homogenization, or precipitation techniques. Exemplarymethods of making nanoparticulate compositions are described in the '684patent.

Methods of making nanoparticulate compositions are also described inU.S. Pat. No. 5,518,187 for “Method of Grinding PharmaceuticalSubstances;” U.S. Pat. No. 5,718,388 for “Continuous Method of GrindingPharmaceutical Substances;” U.S. Pat. No. 5,862,999 for “Method ofGrinding Pharmaceutical Substances;” U.S. Pat. No. 5,665,331 for“Co-Microprecipitation of Nanoparticulate Pharmaceutical Agents withCrystal Growth Modifiers;” U.S. Pat. No. 5,662,883 for“Co-Microprecipitation of Nanoparticulate Pharmaceutical Agents withCrystal Growth Modifiers;” U.S. Pat. No. 5,560,932 for“Microprecipitation of Nanoparticulate Pharmaceutical Agents;” U.S. Pat.No. 5,543,133 for “Process of Preparing X-Ray Contrast CompositionsContaining Nanoparticles;” U.S. Pat. No. 5,534,270 for “Method ofPreparing Stable Drug Nanoparticles;” U.S. Pat. No. 5,510,118 for“Process of Preparing Therapeutic Compositions ContainingNanoparticles;” and U.S. Pat. No. 5,470,583 for “Method of PreparingNanoparticle Compositions Containing Charged Phospholipids to ReduceAggregation,” all of which are specifically incorporated by reference.

The resultant nanoparticulate megestrol compositions can be utilized insolid or liquid dosage formulations, such as controlled releaseformulations, solid dose fast melt formulations, aerosol formulations,lyophilized formulations, tablets, capsules, etc.

1. Milling to Obtain Nanoparticulate Megestrol Dispersions

Milling megestrol to obtain a nanoparticulate megestrol dispersioncomprises dispersing megestrol particles in a liquid dispersion mediumin which megestrol is poorly soluble, followed by applying mechanicalmeans in the presence of grinding media to reduce the particle size ofmegestrol to the desired effective average particle size. The dispersionmedium can be, for example, water, safflower oil, ethanol, t-butanol,glycerin, polyethylene glycol (PEG), hexane, or glycol.

The megestrol particles can be reduced in size in the presence of atleast one surface stabilizer. Alternatively, the megestrol particles canbe contacted with one or more surface stabilizers after attrition. Othercompounds, such as a diluent, can be added to the megestrol/surfacestabilizer composition either before, during, or after the sizereduction process. Dispersions can be manufactured continuously or in abatch mode.

2. Precipitation to Obtain Nanoparticulate Megestrol Compositions

Another method of forming the desired nanoparticulate megestrolcomposition is by microprecipitation. This is a method of preparingstable dispersions of poorly soluble active agents in the presence ofone or more surface stabilizers and one or more colloid stabilityenhancing surface active agents free of any trace toxic solvents orsolubilized heavy metal impurities. Such a method comprises, forexample: (1) dissolving megestrol in a suitable solvent; (2) adding theformulation from step (1) to a solution comprising at least one surfacestabilizer; and (3) precipitating the formulation from step (2) using anappropriate non-solvent. The method can be followed by removal of anyformed salt, if present, by dialysis or diafiltration and concentrationof the dispersion by conventional means.

3. Homogenization to Obtain Nanoparticulate Megestrol Compositions

Exemplary homogenization methods of preparing nanoparticulate activeagent compositions are described in U.S. Pat. No. 5,510,118, for“Process of Preparing Therapeutic Compositions ContainingNanoparticles.”

Such a method comprises dispersing megestrol particles in a liquiddispersion medium, followed by subjecting the dispersion tohomogenization to reduce the particle size of the megestrol to thedesired effective average particle size. The megestrol particles can bereduced in size in the presence of at least one surface stabilizer.Alternatively, the megestrol particles can be contacted with one or moresurface stabilizers either before or after attrition. Other compounds,such as a diluent, can be added to the megestrol/surface stabilizercomposition either before, during, or after the size reduction process.Dispersions can be manufactured continuously or in a batch mode.

D. Methods of Using Nanoparticulate Megestrol Formulations of theInvention

1. Applications of the Nanoparticulate Compositions of the Invention

The nanoparticulate megestrol compositions of the invention may be usedas an appetite stimulant to treat wasting conditions or cachexia. Asused herein, the term “wasting” is used to mean a condition where thepatient is losing body mass as a side effect of a disease progression, adisease treatment, or other condition. Examples of conditions wherewasting is prevalent include, but are not limited to, HIV or AIDS,cancer, cachexia and anorexia.

Additional conditions where the nanoparticulate megestrol compositionsof the invention may be used include, but are not limited to, neoplasticdiseases where the disease normally regresses or the patient's symptomsare normally reduced in response to megestrol, or any other progestin.

The nanoparticulate megestrol compositions of the invention may also beused to treat conditions such as breast cancer, endometrial cancer,uterine cancer, cervical cancer, prostate cancer, and renal cancer. Asused herein, the term “cancer” is used as one of ordinary skill in theart would recognize the term. Examples of cancers include, but are notlimited to, neoplasias (or neoplasms), hyperplasias, dysplasias,metaplasias, and hypertrophies. The neoplasms may be benign ormalignant, and they may originate from any cell type, including but notlimited to epithelial cells of various origin, muscle cells, andendothelial cells.

The present invention also provides methods of hormone replacementtherapy in post-menopausal women, or in subjects after castration,comprising administering a nanoparticulate megestrol composition of theinvention. Further, the compositions of the present invention may beused for ovarian suppression in several situations such asendometriosis, hirsutism, dysmenorrhea, and uterine bleeding.

The present invention also provides methods of oral contraceptioncomprising administering a nanoparticulate megestrol composition of theinvention. In one embodiment, the compositions of the invention areadministered in combination with estrogen or a synthetic estrogen.

2. Dosage Forms of the Invention

The nanoparticulate megestrol compositions of the invention can beadministered to a subject via any conventional means including, but notlimited to, orally, rectally, ocularly, parenterally (e.g., intravenous,intramuscular, or subcutaneous), intracisternally, pulmonary,intravaginally, intraperitoneally, locally (e.g., powders, ointments ordrops), or as a buccal or nasal spray. As used herein, the term“subject” is used to mean an animal, preferably a mammal, including ahuman or non-human. The terms patient and subject may be usedinterchangeably.

Moreover, the nanoparticulate megestrol compositions of the inventioncan be formulated into any suitable dosage form, including but notlimited to liquid dispersions, gels, aerosols, ointments, creams,controlled release formulations, fast melt formulations, lyophilizedformulations, tablets, capsules, delayed release formulations, extendedrelease formulations, pulsatile release formulations, and mixedimmediate release and controlled release formulations.

Nanoparticulate megestrol compositions suitable for parenteral injectionmay comprise physiologically acceptable sterile aqueous or nonaqueoussolutions, dispersions, suspensions or emulsions, and sterile powdersfor reconstitution into sterile injectable solutions or dispersions.Examples of suitable aqueous and nonaqueous carriers, diluents,solvents, or vehicles including water, ethanol, polyols(propyleneglycol, polyethylene-glycol, glycerol, and the like), suitablemixtures thereof, vegetable oils (such as olive oil) and injectableorganic esters such as ethyl oleate. Proper fluidity can be maintained,for example, by the use of a coating such as lecithin, by themaintenance of the required particle size in the case of dispersions,and by the use of surfactants.

The nanoparticulate megestrol compositions may also contain adjuvantssuch as preserving, wetting, emulsifying, and dispensing agents.Prevention of the growth of microorganisms can be ensured by variousantibacterial and antifungal agents, such as parabens, chlorobutanol,phenol, sorbic acid, and the like. It may also be desirable to includeisotonic agents, such as sugars, sodium chloride, and the like.Prolonged absorption of the injectable pharmaceutical form can bebrought about by the use of agents delaying absorption, such as aluminummonostearate and gelatin.

Solid dosage forms for oral administration include, but are not limitedto, capsules, tablets, pills, powders, and granules. In such soliddosage forms, the active agent is admixed with at least one of thefollowing: (a) one or more inert excipients (or carriers), such assodium citrate or dicalcium phosphate; (b) fillers or extenders, such asstarches, lactose, sucrose, glucose, mannitol, and silicic acid; (c)binders, such as carboxymethylcellulose, alignates, gelatin,polyvinylpyrrolidone, sucrose, and acacia; (d) humectants, such asglycerol; (e) disintegrating agents, such as agar-agar, calciumcarbonate, potato or tapioca starch, alginic acid, certain complexsilicates, and sodium carbonate; (f) solution retarders, such asparaffin; (g) absorption accelerators, such as quaternary ammoniumcompounds; (h) wetting agents, such as cetyl alcohol and glycerolmonostearate; (i) adsorbents, such as kaolin and bentonite; and (j)lubricants, such as talc, calcium stearate, magnesium stearate, solidpolyethylene glycols, sodium lauryl sulfate, or mixtures thereof. Forcapsules, tablets, and pills, the dosage forms may also comprisebuffering agents.

Liquid nanoparticulate megestrol dosage forms for oral administrationinclude pharmaceutically acceptable emulsions, solutions, suspensions,syrups, and elixirs. In addition to megestrol, the liquid dosage formsmay comprise inert diluents commonly used in the art, such as water orother solvents, solubilizing agents, and emulsifiers. Exemplaryemulsifiers are ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethylacetate, benzyl alcohol, benzyl benzoate, propyleneglycol,1,3-butyleneglycol, dimethylformamide, oils, such as cottonseed oil,groundnut oil, corn germ oil, olive oil, castor oil, and sesame oil,glycerol, tetrahydrofurfuryl alcohol, polyethyleneglycols, fatty acidesters of sorbitan, or mixtures of these substances, and the like.

Besides such inert diluents, the composition can also include adjuvants,such as wetting agents, emulsifying and suspending agents, sweetening,flavoring, and perfuming agents.

3. Dosage Quantities for the Nanoparticulate Megestrol Compositions ofthe Invention

The present invention provides a method of achieving therapeuticallyeffective plasma levels of megestrol in a subject at a lower dose thanthe standard commercial formulations. This can permit smaller dosingvolumes depending on the megestrol concentration chosen. Such a methodcomprises orally administering to a subject an effective amount of ananoparticulate megestrol composition.

The nanoparticulate megestrol composition, when tested in fastingsubjects in accordance with standard pharmacokinetic practice, producesa maximum blood plasma concentration profile of megestrol of greaterthan about 30 ng/ml in less than about 5 hours after the initial dose ofthe composition.

As used herein, the phrase “maximum plasma concentration” is interpretedas the maximum plasma concentration that megestrol will reach in fastingsubjects.

A suitable dose of megestrol, administered according to the method ofthe invention, is typically in the range of about 1 mg/day to about 1000mg/day, or from about 40 mg/day to about 800 mg/day. Preferably, thetherapeutically effective amount of the megestrol of this invention isabout ⅙, about ⅕, about ¼, about ⅓^(rd), or about ½ of thetherapeutically effective amount of existing commercial megestrolformulations, e.g., Megace®.

“Therapeutically effective amount” as used herein with respect to a drugdosage, shall mean that dosage that provides the specificpharmacological response for which the drug is administered in asignificant number of subjects in need of such treatment. It isemphasized that “therapeutically effective amount,” administered to aparticular subject in a particular instance will not always be effectivein treating the diseases described herein, even though such dosage isdeemed a “therapeutically effective amount” by those skilled in the art.It is to be further understood that drug dosages are, in particularinstances, measured as oral dosages, or with reference to drug levels asmeasured in blood.

One of ordinary skill will appreciate that effective amounts ofmegestrol can be determined empirically and can be employed in pure formor, where such forms exist, in pharmaceutically acceptable salt, ester,or prodrug form. Actual dosage levels of megestrol in thenanoparticulate compositions of the invention may be varied to obtain anamount of megestrol that is effective to obtain a desired therapeuticresponse for a particular composition and method of administration. Theselected dosage level therefore depends upon the desired therapeuticeffect, the route of administration, the potency of the administeredmegestrol, the desired duration of treatment, and other factors.

Dosage unit compositions may contain such amounts of such submultiplesthereof as may be used to make up the daily dose. It will be understood,however, that the specific dose level for any particular patient willdepend upon a variety of factors: the type and degree of the cellular orphysiological response to be achieved; activity of the specific agent orcomposition employed; the specific agents or composition employed; theage, body weight, general health, sex, and diet of the patient; the timeof administration, route of administration, and rate of excretion of theagent; the duration of the treatment; drugs used in combination orcoincidental with the specific agent; and like factors well known in themedical arts.

* * *

The following examples are given to illustrate the present invention. Itshould be understood, however, that the invention is not to be limitedto the specific conditions or details described in these examples.Throughout the specification, any and all references to a publiclyavailable document, including a U.S. patent, are specificallyincorporated by reference.

In the examples that follow, the value for D50 is the particle sizebelow which 50% of the megestrol particles fall. Similarly, D90 is theparticle size below which 90% of the megestrol particles fall.

The formulations in the examples that follow were also investigatedusing a light microscope. Here, “stable” nanoparticulate dispersions(uniform Brownian motion) were readily distinguishable from “aggregated”dispersions (relatively large, nonuniform particles without motion).Stable, as known in the art and used herein, means the particles don'tsubstantially aggregate or ripen (increase in fundamental particlesize).

Example 1

The purpose of this example was to describe preparation ofnanoparticulate dispersions of megestrol acetate.

Formulations 1, 2, 3, 4 and 5, shown in Table 1, were milled under highenergy milling conditions using a NanoMill® (Elan Drug Delivery, Inc.)(see e.g., WO 00/72973 for “Small-Scale Mill and Method Thereof”) and aDyno®-Mill (Willy Bachofen AG).

TABLE 1 Quantity Identity and Quantity Identity and Quantity of ofPrimary Surface of Secondary Surface Mean Formulation MegestrolStabilizer Stabilizer (nm) D90 (nm) 1 5% 1% HPC-SL 0.05% DOSS 167 224 25% 1% HPMC 0.05% DOSS 156 215 3 5% 1% PVP 0.05% DOSS 167 226 4 5% 1%Plasdone ® S630* 0.05% DOSS 164 222 5 5% 1% HPMC 0.05% SLS 148 208*Plasdone ® S630 (ISP) is a random copolymer of vinyl acetate and vinylpyrrolidone.

Formulations 1-5 showed small, well-dispersed particles using the HoribaLa-910 Laser Scattering Particle Size Distribution Analyzer (HoribaInstruments, Irvine, Calif.) and light microscopy. Formulations 1-5 werestable in electrolyte fluids and had acceptable physical stability at 5°C. for 4 weeks. Electrolyte fluids are representative of physiologicalconditions found in the human body. Formulations 1, 2, 3, and 4 alsoexhibited acceptable stability at 25° C. and 40° C. for 4 weeks.Formulation 5 exhibited acceptable stability at 40° C. for at least 3weeks.

Example 2

This example compares the pharmacokinetic parameters of nanoparticulatemegestrol acetate formulations of the present invention withconventional microparticulate formulations of megestrol acetate.

Twelve male beagles, at least twelve months of age, were divided into 2groups based on whether they were fasting or being fed. The dogs wereacclimated for thirteen days prior to dosing. The animals weighedapproximately 11.4 to 14.3 kg at the time of dosing, and the dose wasadjusted to 10 mg/kg. Water was available ad libitum. The animals werefasted (food only) for twelve to sixteen hours prior to dosing on day 1.On day 1, each dog was administered a formulation by gavage. Followingdosing, the gavage tube was flushed with 18 ml of water. In the fedstudy, the animals were fed a high fat meal about 1 hour prior todosing.

The dogs were subdivided into four groups, with each group receivingeither Formulation A (nanoparticulate megestrol dispersion #1,comprising 4.0% megestrol acetate, 0.8% HPMC, and 0.4% DOSS),Formulation B (nanoparticulate megestrol dispersion #2, comprising 4.0%megestrol acetate, 0.8% HPMC, and 0.04% SLS), Formulation C (suspensionof microparticulate megestrol acetate, Par Pharmaceutical, Inc., NewYork) or Formulation D (Megace® Oral Suspension, which is a suspensionof microparticulate megestrol acetate). Each formulation was adjusted toadminister a dose of 10 mg/kg of megestrol acetate to the subject.

Prior to dosing, blood samples were taken from each subject. Bloodsamples were then collected from each subject at 15 and 30 minutes, aswell as 1, 2, 3, 4, 6, 8, 24, 48, and 72 hours after dosing andcentrifuged. Plasma was then separated and diluted when necessary, andsubsequently analyzed for megestrol acetate by HPLC.

Tables 2 and 3 summarize the pharmacokinetic data of the fourformulations administered to fasted dogs and fed dogs, respectively.

TABLE 2 Summary of Pharmacokinetic Data in Fasted Dogs Formulation A n =3 Formulation B n = 3 Formulation C n = 3 Formulation D n = 3 Parameters(Mean ± SD) (Mean ± SD) (Mean ± SD) (Mean ± SD) AUC_(0-t) 37774.23 ±11648.60 21857.68 ± 10737.53 17395.95 ± 10428.73 10094.30 ± 1990.89AUC_(0-inf) 49408.88 ± 3392.80  27863.56 ± 15279.16 6948.48 ± *    12007.13 ± 1923.80 C_(max) 2209.74 ± 351.54  1563.02 ± 787.37  484.98 ±321.70  339.92 ± 175.86 T_(max) 0.83 ± 0.29 0.50 ± 0.00 18.67 ± 9.24  2.67 ± 0.58 t_(1/2) 42.01 ± 33.81 30.09 ± 19.37 26.57 ± *    25.59 ±7.11 K_(el) 0.025 ± 0.018 0.032 ± 0.024 0.026 ± *     0.028 ± .0.007AUC_(0-t) (ng · hr/ml) = Area under the curve from time zero to the lastmeasurable concentration; AUC_(0-inf) (ng · hr/ml) = Area under thecurve from time zero to infinity; C_(max) (ng/ml) = Maximum plasmaconcentration; T_(max) (hr) = Time to occurrence of C_(max); t_(1/2)(hr) = Apparent elimination half-life; K_(el) (1/hr) = elimination rateconstant; * n = 1.

TABLE 3 Summary of Pharmacokinetic Data in Fed Dogs Formulation AFormulation B Formulation C Formulation D n = 3 n = 3 n = 3 n = 3Parameters (Mean ± SD) (Mean ± SD) (Mean ± SD) (Mean ± SD) AUC_(0-t)48543.56 ± 11608.55 36687.92 ± 12016.26 27332.11 ± 6488.79 31397.16 ±5823.79  AUC_(0-inf) 61734.90 ± 4918.52  42787.74 ± 14630.92 31720.98 ±5580.32 40218.66 ± 8649.33* C_(max) 3777.34 ± 2489.41 2875.82 ± 1334.322180.73 ± 406.28 2577.83 ± 665.31  T_(max) 1.67 ± 2.02 3.00 ± 4.33  1.00± 0.00 0.83 ± 0.29 T_(1/2) 34.35 ± 12.10 26.67 ± 7.80   26.16 ± 10.8836.60 ± 9.62* K_(el) 0.022 ± 0.009 0.028 ± 0.010  0.31 ± 0.16  0.20 ±0.005 AUC_(0-t) (ng · hr/ml) = Area under the curve from time zero tothe last measurable concentration; AUC_(0-inf) (ng · hr/ml) = Area underthe curve from time zero to infinity; C_(max) (ng/ml) = Maximum plasmaconcentration; T_(max) (hr) = Time to occurrence of C_(max); t_(1/2)(hr) = Apparent elimination half-life; K_(el) (1/hr) = elimination rateconstant; *n = 2.

The results in the fasted dogs show that the nanoparticulate megestrolformulations (Formulations A and B) showed dramatically superiorbioavailability, as evidenced by the superior AUC and C_(max) results,as compared to the conventional microparticulate megestrol formulations(Formulations C and D). Formulation A, with a C_(max) of 2210, had amaximum concentration more than 4½ times that of Formulation C (485),and a maximum concentration more than 6½ times that of Formulation D(340). Formulation B, with a C_(max) of 1563, had a maximumconcentration more than 3.2 times that of Formulation C (485), and amaximum concentration more than 4.6 times that of Formulation D (340).Also, Formulation A, with an AUC of 49,409 ng hr/mL, had an oralbioavailability more than 7 times that of Formulation C (6948 ng hr/mL)and an oral bioavailability of more than 4 times that of Formulation D(12007 ng hr/mL). Formulation B, with an AUC of 27,864 ng hr/mL, had anoral bioavailability more than 4 times that of Formulation C (6949 nghr/mL) and an oral bioavailability more than 2 times that of FormulationD (12,007 ng hr/mL).

In addition, in the fasted dogs the nanoparticulate megestrolformulations (Formulations A and B) showed dramatically superior fasteronset of action, as evidenced by the superior T_(max) results, ascompared to the conventional microparticulate megestrol formulations(Formulations C and D). Formulation A, with a T_(max) of 0.83 hr,reached a maximum concentration of megestrol in less than 1/20^(th) thetime of Formulation C (18.67 hr), and in less than ⅓^(rd) the time ofFormulation D (2.67 hr). Formulation B, with a T_(max) of 0.50 hr,reached a maximum concentration in less than 1/37^(th) the time ofFormulation C (18.67 hr), and in less than ⅕^(th) the time ofFormulation D (2.67 hr).

Similarly, the results in the fed dogs show that the nanoparticulatemegestrol formulations (Formulations A and B) showed dramaticallysuperior bioavailability, as evidenced by the superior AUC and C_(max)results, as compared to the conventional microparticulate megestrolformulations (Formulations C and D). Formulation A, with a C_(max) of3777, had a maximum concentration of about more than 1.7 times that ofFormulation C (2181), and a maximum concentration of about more than 1.5times that of Formulation D (2578). Formulation B, with a C_(max) of2876, had a maximum concentration of about more than 1.3 times that ofFormulation C (2181), and a maximum concentration of about more than 1.1times that of Formulation D (2578). Formulation A, with an AUC of 61,735ng hr/mL, had an oral bioavailability of more than 1.9 times that ofFormulation C (31721 ng hr/mL) and more than 1.5 times that ofFormulation D (40219 ng hr/mL). Formulation B, with an AUC of 42788 nghr/mL, had an oral bioavailability of more than 1.3 times that ofFormulation C (31721 ng hr/mL) and an oral bioavailability of more than1.1 times that of Formulation D (40218 ng hr/mL).

Example 3

This example demonstrates the physical stability of megestrol acetatedispersions at various concentrations and with the addition of sucrose,flavoring, and preservatives.

Megestrol acetate was milled under high energy milling conditions usinga NanoMill™2 System (Elan Drug Delivery, Inc.) in the presence of apreservative/buffer system consisting of sodium benzoate, citric acidmonohydrate, and sodium citrate dihydrate. After milling, the resultingdispersion was diluted with water, sucrose, flavoring, and additionalpreservative/buffer to prepare dispersions containing 3% (w/w), 5%(w/w), or 9% (w/w) megestrol acetate. The resulting formulations areshown in Table 4. The physical stability of the formulations was thenmonitored at 25° C., 40° C., and 50° C.

TABLE 4 Formulation Summary Concentrated Diluted, Flavored DispersionsNanoparticle Formulation E Formulation F Formulation G Dispersion 3%Dispersion 5% Dispersion 9% Dispersion API and Excipients g/kg g/kg g/kgg/kg Megestrol Acetate, USP 325.000 30.000 50.000 90.000 HydroxypropylMethylcellulose, USP 65.000 6.000 10.000 18.000 Docusate Sodium, USP3.250 0.300 0.500 0.900 Sodium Benzoate, USP 1.214 1.826 1.777 1.681Sodium Citrate Dihydrate, USP 0.910 0.091 0.089 0.084 Citric AcidMonohydrate, USP 0.061 1.369 1.333 1.260 Sucrose, USP 50.000 50.00050.000 Natural and Artificial Lemon Flavor 0.400 0.400 0.400 ArtificialLime Flavor 0.400 0.400 0.400 Purified Water, USP 604.600 909.614885.500 837.280 API = active pharmaceutical ingredient

Particle size measurements (Table 5) were used to assess the physicalstability. The results show almost no increase in the mean particle sizeat either 25° C. or 40° C., and only a slight increase in the meanparticle size at 50° C. 126 days of stability measurements were obtainedfor the 5% and 9% dispersions and 33 days of stability were obtained forthe 3% dispersion, which was prepared at a later date.

TABLE 5 Mean particle size (nm) 3% Dispersion 5% Dispersion 9%Dispersion 25° C. 40° C. 50° C. 25° C. 40° C. 50° C. 25° C. 40° C. 50°C.  0 days 148 148 148 169 169 169 169 169 169 30 days 172 171 187 172170 179 33 days 141 144 173 126 days  171 174 188 168 175 182

Example 4

The purpose of this Example was to demonstrate the improved viscositycharacteristics of the dispersions of this invention.

The viscosities of three formulations of this invention (E, F, and Gasdescribed in Example 3) and two conventional commercial formulations(Formulations C and D as described in Example 2) were determined using arheometer (model CVO-50, Bohlin Instruments). The measurements wereperformed at a temperature of 20° C. using a double gap (40/50)geometry.

The viscosities of the Formulations of this invention were found to benearly Newtonian (i.e., the viscosity being independent of shear rate),and were 1.5, 2.0, and 3.5 mPa s for the 30, 50, and 90 mg/mLconcentrations, respectively.

The viscosity dependence on concentration is illustrated in FIG. 1.

The commercial formulations C and D were shear thinning in nature. Suchsamples cannot be characterized by a single viscosity but rather aseries of viscosities measured at different shear rates. This is mostconveniently illustrated as viscosity-shear rate curves as shown in FIG.2.

The commercial samples and the three formulations of this invention arecompared in Table 6 below. Viscosities are in units of mPa s.

TABLE 6 Shear Rates of Commercial Megestrol Formulations (D and C) andthe Nanoparticulate Megestrol Formulations of the Invention (E, F, & G)Commercial Samples Formulations E, F, & G Shear Formulation Formulation(E) (F) (G) Rate D C 30 mg/mL 50 mg/mL 90 mg/mL s⁻¹ (mPa s) (mPa s) (mPas) (mPa s) (mPa s) 0.1 4010 2860 1.5 2.0 3.5 1 929 723 ″ ″ ″ 10 215 183″ ″ ″ 100 49.9 46.3 ″ ″ ″ * These samples were not measured at the 0.1and 1 s⁻¹ shear rates (the shear range was ca 2 to 100 s⁻¹) but theassessment that these exhibit Newtonian flow properties justifies theentries.

Example 5

The purpose of this Example was to visually demonstrate the differencebetween the viscosity characteristics of liquid megestrol formulationsof the invention as compared to conventional liquid megestrolformulations.

A sample of a 50 mg/mL nanoparticulate dispersion of megestrol acetateand two conventional commercial formulations at 40 mg/mL (Formulations Cand D as described in Example 2) were each placed in a vial, which wasthen shaken. Attached as FIG. 3 is a photograph of the three vials,which from left to right are the nanoparticulate megestrol acetatedispersion, Formulation C, and Formulation D.

The vial with the nanoparticulate dispersion shows a thin, silky, almostshear film coating the vial. In contrast, the vials containing the twocommercial formulations show a gritty residue coating. Such a grittyresidue is the same residue which coats a patient's mouth and throatupon administration. Such a coating is highly unpleasant, particularlyfor patients suffering from wasting (i.e., unable to eat). Thus, FIG. 3visually demonstrates the appeal of a liquid oral nanoparticulatemegestrol formulation of the invention as compared to conventionalcommercial liquid oral megestrol formulations.

Example 6

The purpose of this example was to prepare nanoparticulate compositionsof megestrol acetate using various surface stabilizers.

5% megestrol acetate (Par Pharmaceuticals, Inc.) was combined with 1.25%of various surface stabilizers: tyloxapol (Sterling Organics), Tween 80(Spectrum Quality Products), Pluronic F-108 (BASF), Plasdone S-630(ISP), hydroxypropylmethylcellulose (HPMC) (Shin Etsu),hydroxypropylcellulose (HPC-SL) (Nippon Soda Co., Ltd.), Kollidon K29/32(polyvinylpyrrolidone) (ISP), or lysozyme (Fordras).

For each combination of megestrol acetate and surface stabilizer, thesurface stabilizer was first dissolved in 7.875 g water for injection(WFI) (Abbott Laboratories, Inc.), followed by the addition of themilling media, PolyMill™-500 (Dow Chemical, Co.), and 0.42 g megestrol.

The slurries were charged into each of eight 18 cc NanoMill® (Elan DrugDelivery) chambers and milled for 30 min. Upon completion of milling thedispersions were harvested with a 26 gauge needle yielding the followingparticle sizes shown in Table 7.

All particle size distribution analyses were conducted on a HoribaLA-910 Laser Light Scattering Particle Size Distribution Analyzer(Horiba Instruments, Irvine, Calif.). RO-water was utilized as theliquid dispersing medium and a flow-through sample cell was used for allmeasurements. All samples were assayed in 150 cc liquid medium.

TABLE 7 Megestrol Conc. Surface Stabilizer/Conc. Mean Particle Size 5%tyloxapol; 1.25% 214 nm 5% Tween 80; 1.25% 210 nm 5% Pluronic F-108;1.25% 459 nm 5% Plasdone S-630; 1.25% 292 nm 5% HPMC; 1.25% 314 nm 5%HPC-SL; 1.25% 623 nm 5% PVP K29/32; 1.25% 24816 nm  5% lysozyme; 1.25%179 nm

The results show that tyloxapol, Tween 80, and lysozyme produced smallparticles without substantial aggregation. Pluronic F-108, PlasdoneS-630, HPMC, HPC-SL, and K29/32 had larger particle sizes, indicatingthat aggregation was occurring. Thus, at the particular concentration ofdrug and surface stabilizer, using the described milling method,Pluronic F-108, Plasdone S-630, HPMC, HPC-SL, and K29/32 were notpreferable surface stabilizers. These surface stabilizers may be usefulin nanoparticulate compositions of megestrol at different drug orsurface stabilizer concentrations, or when used in conjunction withanother surface stabilizer.

Example 7

The purpose of this example was to prepare nanoparticulate compositionsof megestrol acetate using various surface stabilizers.

Megestrol acetate (Par Pharmaceuticals, Inc.) and various surfacestabilizers, as shown in Table 8, were combined and milled, followed bydetermination of the particle size and stability of the resultingcomposition. Materials were obtained as in Example 6.

All of the samples were milled using a Dyno®-Mill (Model KDL-Series,Willy Bachofen AG, Basel, Switzerland) equipped with a 150 cc stainlesssteel batch chamber. Cooling water (approximate temperature 5° C.) wascirculated through the mill and chamber during operation.

All particle size distribution analyses were conducted on a HoribaLA-910 Laser Light Scattering Particle Size Distribution Analyzer(Horiba Instruments, Irvine, Calif.), as described above in Example 6.

Qualitative microscopic assessments of the formulations were performedusing a Leica light microscope (Type 301-371.010). Sample preparationinvolved diluting the product dispersions in RO-water and dispensingabout 10 μL onto a glass slide. Oil immersion was utilized inconjunction with 1000× magnification.

The physical stability was assessed by storing the dispersion is 20 mlglass scintillation vials in a temperature/humidity controlled chamberat either 5° C., (25° C./60% RH), (40° C./75% RH), (50° C./75% RH), or55° C. Samples were taken at varying time intervals and the particlesize was analyzed.

For all formulations, the surface stabilizer(s) was first dissolved inWFI (Abbott Laboratories, Inc.) (75.0 g for Exp. Nos. 1, 2, 3, 7, and 8;75.2 g for Exp. Nos. 4 and 9; 74.9 g for Exp. Nos. 5 and 6; 70.3 g forExp. Nos. 10 and 11), followed by combining the surface stabilizersolution megestrol acetate and PolyMill™-500 polymeric grinding media.This mixture was then added to the appropriate milling chamber, milledfor the time period shown in Table 8, followed by harvesting and vacuumfiltering of the megestrol acetate dispersion.

TABLE 8 Surface Exp. Megestrol Stabilizer(s) and Milling Mean ParticleNo. Conc. Conc. Time Size Stability 1 5% 1.25% lysozyme 20 min. 209 nmThe sample showed substantial aggregation after incubation in normalsaline for 30 minutes as determined by optical microscopy. 2 5% 1.25%Tween 80 75 min. 157 nm Upon storage at 5° C. for 15 days the samplegrew to a mean diameter of 577 nm. 3 5% 1.25% tyloxapol  2 hrs. 208 nmOptical microscopoy revealed the presence of elongated “needle-like”crystals. 4 5% 1% Pluronic F127  2 hrs. 228 nm Upon storage at 25° C.for 5 days the sample grew to a mean diameter of 308 nm. 5 5% 1.25% HPMC75 min. 161 nm Upon storage at 40° C. for 19 days, the sample grew to amean diameter of 171 nm. 0.0625% SLS¹ Incubation for 30 minutes at 40°C. in 0.01N HCl or normal saline resulted in particle sizes of 164 nmand 209 nm, respectively. 6 5% 1.25% HPC-SL, 60 min. 167 nm Upon storageat 40° C. for 15 days, the sample grew to a mean diameter of 194 nm.0.05% SLS Incubation for 30 minutes at 40° C. in 0.01N HCl or normalsaline resulted in particle sizes of 183 nm and 179 nm, respectively. 75% 1.25% HPMC 45 min. 185 nm Upon storage at 40° C. for 6 days, thesample grew to a mean diameter of 313 nm. Incubation for 30 minutes at40° C. in 0.01N HCl or normal saline resulted in particle sizes of 2041nm and 1826 nm, respectively. Optical microscopy revealed aggregation inboth the saline and HCl samples. 8 5% 1.25% HPC-SL 45 min. 176 nm Uponstorage at 40° C. for 6 days, the sample grew to a mean diameter of 244nm. Incubation for 30 minutes at 40° C. in 0.01N HCl or normal salineresulted in particle sizes of 873 nm and 524 nm, respectively. Opticalmicroscopy revealed aggregation in both the saline and HCl samples. 9 5%1% HPMC 70 min. 152 nm Incubation for 30 minutes at 40° C. in 0.01N HClor normal saline resulted in particle 0.05% SLS sizes of 155 nm and 539nm, respectively. Optical microscopy confirmed that aggregation waspresent in the sample incubated in saline. 10 10% 2% HPMC 70 min. 150 nmFollowing harvesting the sample was diluted to 4% API by adding WFI.Upon 0.1% DOSS² storage at 40° C. for 40 days, the sample had a meandiameter of 146 nm. Optical microscopy revealed small, well dispersedparticles. 11 10% 2% HPMC 70 min. 146 nm Upon storage at 40° C. for 19days, the sample had a mean diameter of 149 nm. 0.1% SLS Opticalmicroscopy revealed small, well dispersed particles. 12 10% 4% lysozyme60 min. 108 nm Upon storage at 40° C. for 9 days the sample had a meandiameter of 124 nm. Optical microscopy revealed small, well dispersedparticles. ¹Sodium lauryl sulfate (Spectrum Quality Products) ²DioctylSodium Sulfosuccinate (Cytec)

The results shown in Table 8 indicate that the use of lysozyme (Exp.No. 1) as a surface stabilizer resulted in small well dispersedparticles with a mean particle size of 209 nm, but the formulationshowed aggregation when diluted into a normal saline solution. Amegestrol acetate/tyloxapol sample was also stable at higher drug andstabilizer concentrations (Exp. No. 12).

Tween 80, tyloxapol, and Pluronic F127 (Exp. Nos. 2, 3, and 4) wereeffective primary surface stabilizers and produced well-dispersedparticles without significant aggregation. Stability measurements,however, revealed rapid crystal growth for all three stabilizers. 5%megestrol acetate/1.25% Tween 80 grew from 157 nm to 577 nm after 15days at 5° C. 5% megestrol acetate/1.25% tyloxapol showed needle-likecrystals when observed under optical microscopy. 5% megestrolacetate/1.25% Pluronic F127 grew from 228 nm to 308 nm after 5 days at25° C. Because of the rapid crystal growth observed, Tween 80,tyloxapol, and Pluronic F127 were deemed not suitable surfacestabilizers at the described drug/surface stabilizer concentrationsprepared under the conditions described above.

The HPC-SL formulation (Exp. No. 8) showed substantial aggregationindicating that a secondary charged stabilizer would be needed. SLS wasadded (Exp. No. 6) and the new formulation grew from 167 to 194 nm afterstorage at 40° C. for 15 days and did not show any substantialaggregation upon incubation in either 0.01N HCl or normal saline. TheSLS appeared effective at preventing the aggregation but the sampleshowed some particle size growth.

The HPMC formulation (Exp. No. 7) showed substantial aggregationindicating that a secondary charged stabilizer would be needed. SLS wasadded (Exp. Nos. 5 and 11), and the new formulations showed only minimalgrowth from 161 nm to 171 nm (Exp. No. 5), and from 146 to 149 nm (Exp.No. 11), after storage at 40° C. for 19 days. In addition, thecomposition of Exp. No. 5 did not show any substantial aggregation uponincubation in either 0.01N HCl or normal saline. The SLS was effectiveat preventing the aggregation without causing significant crystalgrowth.

An attempt was made to reduce the concentration of the primary andsecondary stabilizers (Exp. No. 9) and resulted in a post-milling meandiameter of 152 nm. Incubation for 30 minutes at 40° C. in normal salineresulted in particle sizes of 539 nm. Optical microscopy confirmed thataggregation was present in the sample incubated in saline.

Docusate sodium (DOSS) was tried as a secondary stabilizer (Exp. No. 10)and resulted in well-dispersed particles with a mean diameter of 150 nm.Upon storage at 40° C. for 40 days, the sample had a mean diameter of146 nm. Optical microscopy revealed small, well-dispersed particles.DOSS seemed to result in even less particle size growth than SLS.

Example 8

The purpose of this example was to prepare nanoparticulate compositionsof megestrol acetate using various surface stabilizers and furtherincluding preservatives or excipients.

The materials and methods were the same as in Example 7, except that forseveral of the examples different sources of megestrol acetate were used(See Table 9). In addition, for Exp. Nos. 5, a NanoMill® milling system(Elan Drug Delivery) was used. Several different combinations ofmegestrol acetate, surface stabilizer(s), and one or more preservativesor excipients were prepared, following by testing the compositions forparticle size and stability.

The surface stabilizer(s) and one or more preservatives were firstdissolved in WFI, followed by combining the solution with megestrolacetate and the grinding media. This mixture was then added to themilling chamber and milled for the time period set forth in Table 9,below.

For several of the experiments, following milling the megestrol acetatedispersion was combined with a flavored suspension. The stability of theresultant composition was then evaluated.

The formulation details and results are shown in Table 9, below.

TABLE 9 Surface Mean Megestrol Stabilizer(s) Preservatives/ MillingParticle Exp. Conc. and Conc. Excipients Time Size Stability 1 10%   2%HPMC Sodium Benzoate 75 min 146 nm After milling a flavored suspensionwas prepared by adding sucrose  0.1% DOSS (0.4 g), (2.5 g), xanthan gum(0.113 g), glycerol (13.75 g), lemon flavor Sodium Citrate (0.1 g), WFI(18.6 g), and 20.0 g of the milled dispersion. Upon Dihydrate storage at40° C. for 24 days, the sample showed aggregation with a (20 mg) meandiameter of 837 nm. Incubation for 30 minutes at 40° C. in Citric Acid0.01N HCl or normal saline resulted in particle sizes of 206 nm andMonohydrate 3425 nm, respectively. Optical microscopy confirmed that the(0.3 g) sample incubated in saline had aggregated. 2 25%   5% HPMCSodium Benzoate 95 min. See right 16 g of the milled drug dispersion wascombined with sucrose (5 g), 0.05% DOSS (0.11 g) column. lime flavor (80mg), and WFI (78.9 g). The diluted drug dispersion Citric Acid had amean diameter of 192. After 6 days at 55° C. the particles hadMonohydrate a mean diameter of 10 microns, indicating substantialaggregation (0.08 g) 3 25%   5% HPMC, Sodium Benzoate 95 min. See right16 g of the milled drug dispersion was combined with sucrose (5 g),0.15% DOSS (0.11 g) column. lime flavor (80 mg), and WFI (78.9 g). Thediluted drug dispersion Citric Acid had a mean diameter of 173 nm. After12 days at 55° C. the particles Monohydrate had a mean diameter of 295nm. (0.08 g) 4 32.5%1   6.5% HPMC Sodium Benzoate 15.5 hrs 160 nm Uponstorage at 50° C. for 44 days, the mean diameter was 190 nm. 0.33% DOSS(13.07 g) Sodium Citrate Dihydrate (0.65 g) Citric Acid Monohydrate (9.8g) 5 32.5%    6.5% HPMC Sodium Benzoate 12 hrs 147 nm Upon storage at50° C. for 44 days the mean diameter was 178 nm. 0.33% DOSS (9.71 g)Sodium Citrate Dihydrate (0.49 g) Citric Acid Monohydrate (7.28 g)1Pharmacia ²Pharmabios

In Exp. No. 1 of Table 9, a sweetened, flavored dispersion was preparedby mimicking the current commercial formulation of megestrol acetatethat contains sucrose, xanthan gum, glycerol, lemon and lime flavors,and is preserved and buffered with sodium benzoate and citric acid. Uponstorage at 40° C. for 24 days the sample showed aggregation with a meandiameter of 837 nm. Incubation for 30 minutes at 40° C. in 0.01N HCl ornormal saline resulted in particle sizes of 206 nm and 3425 nm,respectively. Optical microscopy confirmed that the sample incubated insaline had aggregated. The aggregation upon storage indicated that thisparticular combination of drug and surface stabilizer, at theconcentrations used and methodology employed to make the compositions,would not be an effective formulation.

For Exp. Nos. 4 and 5, the formulation was scaled-up in a NanoMill™-2system to determine if the scale-up would effect the physical stability.Two different sources of megestrol acetate were tested: Pharmacia andPharmabios. The product of Exp. No. 4 had a mean diameter of 160 nmwithout ultrasound. Upon storage at 50° C. for 44 days the mean diameterwas 190 nm. The composition of Exp. No. 5 had a post-milling meandiameter of 147 nm without ultrasound. Upon storage at 50° C. for 44days the mean diameter was 178 nm. Both sources of active agent milledeffectively and showed little particle size growth even at 50° C.

* * *

The results of Examples 6 and 7 showed that high energy milling withpolymeric attrition media could be used to produce stablenanoparticulate colloidal dispersions of megestrol acetate suitable fororal administration to animals or humans. The primary stabilizer HPMCrequired the presence of DOSS or SLS to prevent aggregation at theconcentrations of drug and stabilizer tested (other combinations of drugand HPMC concentrations may result in a stable composition without theaddition of a second surface stabilizer). In general, average particlesizes of less than about 160 nm could be obtained. Tests conducted withtwo sources of megestrol acetate revealed that both sources milledeffectively and exhibited excellent physical stability.

Based on mean particle size, physical stability, and the pre-clinicaldog study, the best nanoparticulate megestrol acetate formulation forcommercial development, based on the results of the data given in theexamples, consisted of 32.5% megestrol acetate, 6.5% HPMC, and 0.325%DOSS (i.e., a drug:HPMC ratio of 1:5 and a drug:DOSS ratio of 1:100. Theformulation milled effectively in the presence of preserved water (0.2%sodium benzoate, 0.01% sodium citrate dihydrate, and 0.15% citric acidmonohydrate). Upon dilution with preserved water, flavors, and sucrosenone of the dispersions showed severe aggregation, except for thedispersions containing xanthan gum (data not shown) or low levels ofDOSS. The alcohol-based flavors did not effect the physical stabilitynor did several freeze-thaw cycles (data not shown).

Example 9

This example compares the pharmacokinetic parameters of nanoparticulatemegestrol acetate formulations of the invention with a conventionalmicroparticulate formulation of megestrol acetate. Results were obtainedfrom a fasted study group consisting of 36 male subjects, 18 years ofage or older. For a fed study group, results from 32 subjects wereanalyzed.

Subjects in the fasted study group and the fed study group wereadministered study drugs in four successive periods. Treatment A (1×150mg drug as 5 ml of a 3% megestrol acetate nanoparticulate formulation)was administered in the first period. Reference Treatment B (1×800 mgdrug as 20 ml of a 4% megestrol acetate Megace® Oral Suspension) wasadministered in the second period. Treatment C (1×250 mg drug as 5 ml ofa 5% megestrol acetate nanoparticulate formulation) was administered inthe third period. Treatment D (1×450 mg drug as 5 ml of a 9% megestrolacetate nanoparticulate formulation) was administered in the fourthperiod. The formulations of Treatments A, C, and D are listed in Table10 below, with particle size information (microns) provided in Table 11.

In each period, subjects were confined from at least 10 hours prior todrug administration to after the last sample collection. In the fastedstudy group, no food was consumed from at least 10 hours before dosingto at least 4 hours after dosing. In the fed study group, a high-caloriebreakfast (containing about 800 to 1000 calories, approximately 50% ofwhich were from fat) was served within 30 minutes prior to dosing;dosing occurred within 5 minutes after the breakfast was completed. Acontrolled meal was served to both groups after 4 hours after dosing,and standard meals were served at appropriate times thereafter. Themeals in all four periods were identical. Subjects in the fasted studygroup were not allowed fluid intake from 1 hour before dosing to 1 hourafter. Subjects in the fed study group were also not allowed fluidintake during this period except for fluids provided with thehigh-calorie breakfast. Water was provided ad libitum to both studygroups at all other times.

Blood samples were obtained before dosing, at half-hourly intervals inthe 6 hours following dosing, and at 7, 8, 12, 16, 20, 24, 36, 48, 72,and 96 hours after dosing. Megestrol acetate in plasma samples was thendetermined.

Table 12 below summarizes pharmacokinetic data for the fasted studygroup, and Table 13 below summarizes pharmacokinetic data for the fedstudy group.

Treatments A, C, and D in fasting subjects produced dose-normalizedvalues for AUC_(0-t) and AUC_(0-inf) that were approximately twice thoseof Reference Treatment B. Maximum dose-normalized megestrol acetateconcentrations in Treatments A, C, and D were approximately 9 to 12times that of Reference Treatment B. The maximum megestrol acetateconcentration for the 150 mg-dose of Treatment A was approximately twicethat of the 800 mg-dose of reference Treatment B. Moreover, comparablevalues of AUC_(0-t) and AUC_(0-inf) were observed for the 450 mg-dose ofTreatment D and the 800 mg-dose of Reference Treatment B.

Treatments A, C, and D in fed subjects produced dose-normalized valuesfor AUC_(0-t) and AUC_(0-inf) that were approximately 8 to 10% greaterthan those of Reference Treatment B. Maximum dose-normalized megestrolacetate concentrations in Treatments A, C, and D were approximately 38to 46% greater than that of Reference Treatment B. Megestrol acetateonset for Treatments A, C, and D was comparable to Reference TreatmentB.

Nanoparticulate megestrol acetate formulations, therefore, exhibitedsuperior oral bioavailability, relative to the Megace® Oral Suspension,in fasting and fed human subjects.

TABLE 10 Formulations for Megestrol Acetate Oral Suspension 3, 5% and 9%Strengths 3% w/w 5% w/w 9% w/w (30 (50 (90 Ingredients mg/mL) mg/mL)mg/mL) Megestrol Acetate 3.000 5.000 9.000 Hydroxypropyl Methylcellulose0.600 1.000 1.800 Docusate Sodium 0.030 0.050 0.090 Sodium Benzoate0.183 0.178 0.168 Sodium Citrate Dihydrate 0.009 0.009 0.008 Citric AcidMonohydrate 0.137 0.133 0.126 Sucrose 5.000 5.000 5.000 Natural andArtificial Lemon Flavor 0.040 0.040 0.040 Artificial Lime Flavor 0.0400.040 0.040 Purified Water 90.961 88.550 83.727 TOTAL 100.000 100.000100.000

TABLE 11 Particle Size Data for the Megestrol Acetate Oral Suspensions*Strength 30 mg/g Strength 50 mg/g Strength 90 mg/g d(0.1) d(0.5) d(0.9)d(0.1) d(0.5) d(0.9) d(0.1) d(0.5) d(0.9) Initial 0.068 0.123 0.2230.069 0.125 0.229 0.068 0.124 0.227 ACC/1 0.070 0.129 0.237 0.070 0.1270.231 0.070 0.127 0.230 month ACC/2 0.070 0.127 0.231 0.070 0.127 0.2330.073 0.126 0.221 months ACC/3 0.070 0.129 0.237 0.070 0.128 0.235 0.0700.128 0.234 months RT 3 0.070 0.128 0.237 0.073 0.128 0.224 0.067 0.1210.223 months *All particle sizes are given in microns. “d(0.1)” meansdistribution of smallest 10% of the particles, i.e., d(0.1) 10 μm means10% of the particles are less than 10%. Similarly, “d(0.5)” meansdistribution of the smallest 50% of the particles, and “d(0.9)” meansdistribution of the smallest 90% of the particles. Thus, d(0.9) meansthat 90% of the particles are less than XX μm.

TABLE 12 Summary of Pharmacokinetic Data in Fasted Human Subjects*Treatment A Ref. Treatment B Treatment C Treatment D Parameters (Mean ±SD) (Mean ± SD) (Mean ± SD) (Mean ± SD) AUC_(0-t) 2800 ± 900  7000 ±5000 4700 ± 1800 8500 ± 3200 AUC_(0-inf) 3100 ± 1000 9000 ± 9000 5200 ±2100 9000 ± 4000 C_(max) 410 ± 120 190 ± 110 650 ± 200 950 ± 270 T_(max)1.7 ± 0.9 6 ± 6 1.6 ± 1.0 1.7 ± 1.1 t_(1/2) 35 ± 13 31 ± 19 34 ± 10 34 ±12 K_(el) 0.023 ± 0.011 0.026 ± 0.009 0.022 ± 0.008 0.023 ± 0.008AUC_(0-t) (ng · hr/ml) = Area under the curve from time zero to the lastmeasurable concentration; AUC_(0-inf) (ng · hr/ml) = Area under thecurve from time zero to infinity; C_(max) (ng/ml) = Maximum plasmaconcentration; T_(max) (hr) = Time to occurrence of C_(max); t_(1/2)(hr) = Apparent elimination half-life; K_(el) (1/hr) = Elimination rateconstant; *n = 36.

TABLE 13 Summary of Pharmacokinetic Data in Fed Human Subjects*Treatment A Ref. Treatment B Treatment C Treatment D Parameters (Mean ±SD) (Mean ± SD) (Mean ± SD) (Mean ± SD) AUC_(0-t) 3500 ± 1100 17000 ±5000 5700 ± 1600 10500 ± 3000 AUC_(0-inf) 3900 ± 1300 19000 ± 6000 6300± 2000 12000 ± 4000 C_(max) 380 ± 140 1400 ± 400 590 ± 170 1080 ± 290T_(max) 3.8 ± 3.5  3.9 ± 0.9 3.4 ± 1.7  3.2 ± 1.7 t_(1/2) 35 ± 12 33 ± 935 ± 10  38 ± 12 K_(el) 0.023 ± 0.013  0.023 ± 0.007 0.023 ± 0.009 0.021 ± 0.008 AUC_(0-t) (ng · hr/ml) = Area under the curve from timezero to the last measurable concentration; AUC_(0-inf) (ng · hr/ml) =Area under the curve from time zero to infinity; C_(max) (ng/ml) =Maximum plasma concentration; T_(max) (hr) = Time to occurrence ofC_(max); t_(1/2) (hr) = Apparent elimination half-life; K_(el) (1/hr) =Elimination rate constant; *n = 32.

Example 10

This example compares the pharmacokinetic parameters of ananoparticulate megestrol acetate formulations to a conventionalmicroparticulate formulation of megestrol acetate (Megace® by BristolMyers Squibb Co.). Results were obtained from a fasted study groupconsisting of 33 male subjects, 18 years of age or older.

The nanoparticulate megestrol acetate compositions were prepared asdescribed in Example 10.

Subjects were administered study drugs in four successive periods.Treatment A (575 mg of nanoparticulate megestrol acetate formulation in5 ml oral suspension) was administered in the first period. ReferenceTreatment B (800 mg of megestrol acetate (Megace® by Bristol MyersSquibb Co.) in 20 ml oral suspension) was administered in the secondperiod. Treatment C (625 mg of nanoparticulate megestrol acetateformulation in 5 ml oral suspension) was administered in the thirdperiod. Treatment D (675 mg of nanoparticulate megestrol acetateformulation in 5 ml oral suspension) was administered in the fourthperiod.

Table 14 provides the formulations of Treatments A, C and D.

TABLE 14 Formulations of Nanoparticulate Megestrol Acetate OralSuspensions Dosage 115 mg/mL 125 mg/mL 135 mg/mL Conc. Conc. Conc. FINALAMOUNTS Weight (g) (mg/mL) Weight (g) (mg/mL) Weight (g) (mg/mL)Megestrol Acetate 37,500.0 115.00 37,500.0 125.00 37,500.0 135.00 HPMC7,500.0 23.00 7,500.0 25.00 7,500.0 27.00 Docusate Sodium 375.0 1.15375.0 1.25 375.0 1.35 Sodium Benzoate 530.4 1.63 481.4 1.60 439.7 1.58Sodium Citrate Dihydrate 26.5 0.08 24.0 0.08 22.0 0.08 Citric AcidMonohydrate 397.8 1.22 361.1 1.20 329.8 1.19 Sucrose 15,473.0 47.4514,044.0 46.81 12,826.7 46.18 Lemon Flavor 123.8 0.38 112.4 0.37 102.60.37 Lime Flavor 123.8 0.38 112.4 0.37 102.6 0.37 Water 277,080.1 —251,489.7 — 229,690.5 — TOTAL (Weight, g) 339,130.4 312,000.0 —288,888.9 — TOTAL (volume, L) 326.1 300.0 — 277.8 —

The nanoparticulate megestrol acetate formulations were prepared bymilling a concentrated dispersion of the drug substance followed bydilution to yield the final products. Hydroxypropyl methylcellulose anddocusate sodium were used as stabilizing agents. The formulations wereprocessed in a NanoMill-10 horizontal media mill (Netzsch USA) for 20hours. The attrition media used was 500 μm crosslinked polystyrene(PolyMill™-500). The dispersion further comprised 0.13% sodium benzoate,0.01% sodium citrate dihydrate, and 0.1% citric acid monohydrate. Milleddispersion was diluted to final megestrol acetate concentrations of 115mg/mL (575 mg/5 mL), 125 mg/mL (625 mg/5 mL) and 135 mg/mL (675 mg/5mL). The final compositions additionally contained sweetening andflavoring agents.

Particle size determinations were performed on a Malvern Mastersizer2000 instrument. The particle size distributions of the nanoparticulatemegestrol acetate compositions are provided in Table 15.

TABLE 15 Concentration (mg/mL) Mean particle size (nm) 50% < (nm) 90% <(nm) 115 144 130 234 125 144 127 237 135 145 131 236

In each period, subjects were confined from at least 11 hours prior todrug administration until after the 24.0 hour post-dose samplecollection. After a supervised fast of at least 10 hours, subjects werefed a high-calorie meal containing about 800 to 1000 calories(approximately 150 calories from carbohydrates and 500-600 calories fromfat). The meal consisted of two eggs fried in butter, two slices oftoast with butter, two strips of bacon, approximately 128 g of hashbrown potatoes and 200 ml of whole milk. The meals in all four periodswere identical. The meal was completed within 30 minutes, and subjectswere dosed 30 minutes after starting the meal.

The suspensions of Treatments A, B, C and D were administered via SlipTip syringe directly into the mouth and swallowed. The syringe wasrinsed three (3) times with approximately 5 ml (Treatments A, C and D)or 20 ml (Treatment B) of water. Following drug administration,approximately 225 ml (Treatments A, C and D) or 180 ml (Treatment B) ofwater was ingested.

For each period, a total of 24 blood samples were drawn from eachsubject. Blood samples were collected in EDTA blood tubes prior to drugadministration and 0.250, 0.500, 0.750, 1.00, 1.50, 2.00, 2.50, 3.00,3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 8.00, 12.0, 16.0, 20.0, 24.0, 36.0,48.0, 72.0 and 96.0 hours post-dose (1×7 mL for each sampling time).

Table 16 below summarizes the pharmacokinetic data, while Table 17provides the statistical comparisons of the treatments.

TABLE 16 Pharmmacokinetic Parameters Test-1 (Megtestrol Acetate 575 mg/5mL (A)) Reference: (Megace 40 mg/mL (B)) Parameters Mean ± SD CV (%)Mean ± SD Cv (%) AUC_(o-t) (ng-h/mL) 13657.52 ± 3900.50  28.56 16896.21± 4942.51  29.25 AUC_(o-inf) (ng-h/mL) 14743.33 ± 4451.31  30.1918274.06 ± 5623.07  30.77 C_(max) (ng/mL) 1420.73 ± 420.79  2962 1400.66± 350.57  25.03 T_(max) (h) 3.75 ± 1.57 41.85 3.88 ± 1.02 26.38 T_(max)*(h) 4.50 ± 1.00 — 4.50 ± 1.00 — K_(el) (h⁻¹) 0.0224 ± 0.0062 27.440.0238 ± 0.0054 22.84 T_(1/2 el) (h) 32.78 ± 7.47  22.80 30.53 ± 6.66 21.80 Test-2 (Megtestrol Acetate Test-3 (Megestrol 625 mg/5 mL (C))Acetate 675 mg/5 ml (D)) Parameters Mean ± SD CV (%) ± ± SD Cv (%)Auc_(o-t) (ng-h/mL) 14682.37 ± 4844.60  33.00 15323.29 ± 4525.94  29.54AUC_(o-inf) (ng-h/mL) 16081.76 ± 5563.09  34.59 16738.88 ± 5432.52 32.45 C_(max) (ng/mL) 1516.79 ± 389.01  25.65 1645.74 ± 455.71  27.69T_(max) (h) 2.52 ± 1.60 63.52 3.13 ± 1.64 52.55 T_(max)* (h) 2.50 ± 3.50— 3.50 ± 3.00 — K_(el) (h⁻¹) 0.0211 ± 0.0055 26.21 0.0211 ± 0.0054 25.64T_(1/2 el) (h) 34.75 ± 7.81  22.48 34.83 ± 8.12  23.30 *Median andinterquartile ranges are presented. AUC_(o-t) (ng · h/ml) = Area underthe curve from time zero to the last measurable concentrationAUC_(o-inf) (ng · h/ml) = Area under the curve from time zero toinfinity C_(max) (ng/ml) = Maximum plasma concentration T_(max) (h) =Time to occurrence of C_(max) t_(1/2 el) (h) = elimination half-lifeK_(el) (1/h) = elimination rate constant

TABLE 17 Treatment Comparisons Statistical Intra- Analysis Treatment 90%Geometric CL² Subject (ANOVA) Comparisons Ratio¹ Lower Upper CVAUC_(o-t) Megestrol Actate 575 mg/5 mL (A) vs 81.06% 78.20% 84.03% 8.82%Megace 40 mg/mL (B) Megestrol Actate 625 mg/5 mL (C) vs 86.29% 83.24%89.45% Megace 40 mg/mL (B) Megestrol Actate 675 mg/5 mL (D) vs 90.63%87.43% 93.95% Megace 40 mg/mL (B) AUC_(o-inf) Megestrol Actate 575 mg/5mL (A) vs 80.92% 77.95% 84.00% 9.16% Megace 40 mg/mL (B) MegestrolActate 625 mg/5 mL (C) vs 87.33% 84.12% 90.65% Megace 40 mg/mL (B)Megestrol Actate 675 mg/5 mL (D) vs 91.31% 87.96% 94.79% Megace 40 mg/mL(B) C_(max) Megestrol Actate 575 mg/5 mL (A) vs 100.62% 94.10% 107.69%16.51% Megace 40 mg/mL (B) Megestrol Actate 625 mg/5 mL (C) vs 108.18%101.17% 115.69% Megace 40 mg/mL (B) Megestrol Actate 675 mg/5 mL (D) vs116.72% 109.15% 124.82% Megace 40 mg/mL (B) ¹Calculated usingleast-squares means ²90% Geometric Confidence Interval usingIn-transformed data

Tables 16 and 17 demonstrate that Treatments A, C, and D producedsimilar pharmakinetics as Treatment B. FIGS. 4 and 5 show thatTreatments A, C and D produce similar concentration-time curves asTreatment B.

* * *

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the methods and compositionsof the present invention without departing from the spirit or scope ofthe invention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

We claim:
 1. A method of increasing the body mass in a human patientsuffering from anorexia, cachexia, or loss of body mass, comprisingadministering to the human patient a megestrol acetate formulation,wherein: (a) the megestrol acetate formulation is a dose of about 40 mgto about 800 mg in about a 5 mL dose of an oral suspension; (b) themegestrol acetate formulation comprises megestrol acetate particles,wherein about 80% of the particles are between or equivalent to about250 nm and about 50 nm, and at least one surface stabilizer isassociated with the surface of the megestrol acetate particles; and (c)the administration is once daily; wherein after a single administrationin a human subject of the formulation the difference in the C_(max) ofthe megestrol acetate when administered in a fed versus a fasted stateis less than about 100%, wherein fasted state is defined as the subjecthaving no food within at least the previous 10 hours, and wherein fedstate is defined as the subject having a high-calorie meal withinapproximately 30 minutes of dosing.
 2. The method of claim 1, whereinabout 80% of the particles are between or equivalent to about 230 nm andabout 70 nm.
 3. The method of claim 1, wherein the anorexia, cachexia orloss of body mass is associated with a diagnosis of HIV or AIDS in thehuman patient.
 4. The method of claim 1, wherein the anorexia, cachexiaor loss of body mass is associated with a diagnosis of cancer in thehuman patient.
 5. The method of claim 1, wherein the difference in_(Cmax) of the megestrol when administered in a fed versus a fastedstate is less than about 90%, less than about 80%, less than about 70%,or less than about 60%.
 6. The method of claim 1, wherein the differencein _(Cmax) of the megestrol when administered in a fed versus a fastedstate is less than about 50%.
 7. The method of claim 1, wherein thedifference in C_(max) of the megestrol when administered in a fed versusa fasted state is less than about 40%.
 8. The method of claim 1, whereinthe difference in C_(max) of the megestrol when administered in a fedversus a fasted state is less than about 30%.
 9. The method of claim 1,wherein the difference in C_(max) of the megestrol when administered ina fed versus a fasted state is less than about 20%.
 10. The method ofclaim 1, wherein the difference in C_(max) of the megestrol whenadministered in a fed versus a fasted state is less than about 15%. 11.The method of claim 1, wherein the difference in C_(max) of themegestrol when administered in a fed versus a fasted state is less thanabout 10%.
 12. The method of claim 1, wherein the difference in C_(max)of the megestrol when administered in a fed versus a fasted state isless than about 5%.
 13. The method of claim 1, wherein the difference inC_(max) of the megestrol when administered in a fed versus a fastedstate is less than about 3%.
 14. The method of claim 1, wherein there isa difference in the mean T_(max) for the megestrol acetate formulationwhen administered in fed versus fasted states, and that difference isselected from the group consisting of less than about 100%, less thanabout 90%, less than about 80%, less than about 70%, less than about60%, less than about 50%, less than about 40%, less than about 30%, lessthan about 20%, less than about 15%, less than about 10%, less thanabout 5%, and less than about 3%.
 15. The method of claim 1, wherein theformulation exhibits a mean _(Cmax) selected from the group consistingof greater than about 5%, greater than about 10%, greater than about15%, greater than about 20%, greater than about 30%, greater than about40%, greater than about 50%, greater than about 60%, greater than about70%, greater than about 80%, greater than about 90%, greater than about100%, greater than about 110%, greater than about 120%, greater thanabout 130%, greater than about 140%, and greater than about 150% thanthe mean C_(max) exhibited by a standard commercial, non-nanoparticulatecomposition of megestrol, administered at the same dosage.
 16. Themethod of claim 1, wherein there is a difference in absorption (AUC)when the megestrol acetate formulation is administered in fed versusfasted states, and the difference is selected from the group consistingof less than about 35%, less than about 30%, less than about 25%, lessthan about 20%, less than about 15%, less than about 10%, less thanabout 5%, and less than about 3%.
 17. The method of claim 1, wherein amaximum blood plasma concentration of megestrol is attained in about 1hour or less after administration of the megestrol formulation infasting subjects.
 18. The method of claim 1, wherein a maximum bloodplasma concentration of megestrol of at least about 700 ng/ml isobtained.
 19. The method of claim 18, wherein the maximum blood plasmaconcentration of megestrol is at least about 700 ng/ml and is attainedin less than 5 hours after administration of the megestrol formulation.20. The method of claim 1, wherein the maximum blood plasmaconcentration of megestrol is at least about 400 ng/ml and is attainedin less than 5 hours after administration of the megestrol formulation.21. The method of claim 1, wherein a mean C_(max) of about 300 ng/ml toabout 2000 ng/ml is obtained after a single administration of theformulation in the human subject in a fasted state.
 22. The method ofclaim 1, wherein the surface stabilizer is selected from the groupconsisting of nonionic surfactants, cationic surfactants, ionicsurfactants, and zwitterionic surfactants.
 23. The method of claim 1,wherein the surface stabilizer is selected from the group consisting ofhydroxypropyl methylcellulose, hydroxypropylcellulose,polyvinylpyrrolidone, sodium lauryl sulfate, dioctylsulfosuccinate,polyoxyethylene alkyl etherspolyoxyethylene sorbitan fatty acid esters,4-(1,1,3,3-tetramethylbutyl)-phenol polymer with ethylene oxide andformaldehyde, lysozyme, and random copolymers of vinyl pyrrolidone andvinyl acetate.
 24. The method of claim 23, wherein the surfacestabilizer is selected from the group consisting of hydroxypropylmethylcellulose, dioctylsulfosuccinate, and a combination thereof.